Video Game / Metal Slug

Mission One, Start!

Metal Slug is a series of games from SNK.^note The first game was actually created by Nazca Corporation, a company founded by former Irem employees after the closure of Irem's arcade division in 1994 and merged into SNK a few years later, losing the Nazca name in the process. Basically, it's a Run-and-Gun Shoot 'Em Up series. Shoot everything that takes damage, rescue prisoners, collect power-ups from their underwear, and do your best to stay alive.

The series' name refers to the incredibly cool, heavily armed one-seater tankette shown to your right. It can duck, it can jump, it's got two Vulcan miniguns... and the lowest-velocity high explosive cannon the world has ever seen. If you're truly desperate you can cause it to self-destruct, ejecting you into a somersault and rushing headlong into the enemy before blowing up.

The rather threadbare (at least in the games proper) stories usually involve the general Donald Morden, who is leading a rebel army to take control of the world. Over the course of the series, he makes deals with rebels, mad scientists, demons, and even aliens in his bid to change the world.

The series began with the Peregrine Falcon squad, Marco and Tarma, then added the Sparrows team, Eri and Fio, who together all form the core of the series. The fourth game relegated Tarma and Eri to the sidelines, while newcomers Trevor and Nadia took their places for a while. The sixth game notably added Ralf and Clark, the Ikari Warriors who have spent the last decade or so hanging out in The King of Fighters series. Their KoF teammate Leona Heidern is also available in Metal Slug XX as a downloadable character.

An interesting feature is semi-realistic personnel damage - one hit and you die - which applies to the characters and most of the mooks as well. If you're in a vehicle, you're in luck - you get three hit points, and once you lose them, you can still eject. Did we mention that very few enemies have touch-of-death? Well, it is so - if you want to kill someone you actually need to shoot or slice 'em with a melee weapon, and the same is true for them. Don't let this fool you though: the games are mercilessly hard, but in a way that makes you keep wanting to try again. Also, if a tank runs you over, though, it'll still kill you - unless you have a tank of your own.

Much of the game's appeal stems from its detailed, fluid graphics; it employs hand-drawn animation created by artists failing to understand the concepts of immovable chins or kneeless legs. Nuanced touches abound, such as multiple melée and idle animations for both enemies and the player characters. The artists also went to the trouble of making reloading animations which trigger after an appropriate number of bullets have been fired, even though you don't actually need to reload at any point. Even the enemy grunts are quite varied; they eat, talk amongst themselves, and occasionally run screaming in terror. Of course, they also have a nasty habit of jumping on your 'slug and humping the main cannon to stop you from firing. All in all, it is a great example of how to convey a huge amount of personality without any dialog or cutscenes.

There is also a free-to-play tower defense/base assault game that brings together all the mooks and characters from the universe together. Go here to read more.

A remake, produced by SNK with collaboration from China's Tencent Studios, titled Metal Slug Code J was released in May 2021.

In May 15, 2023, the developers of Metal Slug (under the banner of KohachiStudio) have announced that Black Finger JET, the game's spiritual successor, is in the works.

List of titles:

Main Series

• Metal Slug: Super Vehicle-001 (1996; Neo-Geo, PlayStation)
• Metal Slug 2: Super Vehicle-001/II (1998; Neo-Geo)
  • Metal Slug X: Super Vehicle-001 (1999; Neo-Geo, PlayStation)
• Metal Slug 3 (2000; Neo-Geo, PlayStation 2)
• Metal Slug 4 (2002; Neo-Geo, PlayStation 2)
• Metal Slug 5 (2003; Neo-Geo, PlayStation 2)
• Metal Slug 6 (2006; Sammy Atomiswave, PlayStation 2)
• Metal Slug 7 (2008; Nintendo DS)
  • Metal Slug XX (2009; PlayStation Portable, Xbox 360, PlayStation 4)

Spinoffs

• Metal Slug: 1st Mission (1999; Neo-Geo Pocket Color)
  • Metal Slug: 2nd Mission (2000; Neo-Geo Pocket Color)
• Metal Slug Advance (2004; Game Boy Advance)
• Metal Slug 3D (2006; PlayStation 2) (Japan Only)
• Metal Slug Defense (2014; iOS, Android, Steam)
  • Metal Slug Attack (2016; iOS, Android)
  • Metal Slug Infinity (2019; iOS, Android)
• Metal Slug Commander (2021; iOS, Android)
• Metal Slug Code J (2021; iOS, Android)
• Metal Slug Tactics (TBA; Steam, Switch)
• Metal Slug Awakening (2023; iOS, Android)

Now with its own Character Sheet

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Trope List 1 - START!

• Abnormal Ammo: There is nothing abnormal about bouncing explosive blobs, exploding land-based missile (seemingly taken from Lupin the Third), stones, a knife that creates a wave of energy, a dispenser that creates minature thunder cloud , a floating mini-satellite, a gun that shoots thunder, or a revolver that shoots spinning, exploding rifles.
• Absurdly Spacious Sewer:
  • The fifth mission of Metal Slug 2/X ends up in the sewers under New Godokin City (the in-game equivalent to New York) where the Rebel Army has somehow constructed a secret lab to research making super soldiers (resulting in the inevitable outbreak of mutant zombies). This culminates in a battle with the level boss: a submarine that has somehow been hidden in the sewers to guard the facility.
  • The third mission of Metal Slug 6 likewise ends up in a sewer under a Chinese city where you to battle the boss: a brain in a giant robot. The sewer is big enough that entire trucks are hidden below the waterline which the boss occasionally pulls up to throw at you.
• Acrofatic: Your character can gain some serious weight by eating too much health powerups. Other then slowing them down a bit it doesn't deter their agility a single bit.
• Action Bomb:
  • A few enemies attack by exploding themselves near you, such as the big maggots, the crawling mutants in 2/X, or the Rebel Army zombies in 3.
  • The Fat Lizard ammo, used by the Walker Slugnoid and the Type-R, which is a small ball with legs that runs to the left of the player, then explodes.
• Advancing Boss of Doom:
  • 2 and X has the Aeshi Nero, a giant cobra-like excavator trying to "devour" the pillar you're on. Later on, there were runaway trains in the subway section of the fifth stage that you had to destroy before they pushed you to the side of the screen.
  • 3 has Huge Hermit, which is destroying the bridge you're on by its advance.
  • 6 has the Brain in a Jar alien robot in the sewers.
• Aerith and Bob: You've got regular English names like Trevor, Donald and Allen, not-so-regular Japanese names like Eri, Rumi and Madoka and names that may or may not actually exist like Fiolina and Tarma (Tarmicle). Marco himself zig-zags this one as his real name is Marchrius. The non-Japanese prisoners also count as well.
• Affirmative Action Girl:
  • Eri and Fio were added to the Metal Slug 2 roster, and playable through the rest (except in 4, where Nadia replaces Eri).
  • Metal Slug XX added Leona from The King of Fighters as optional DLC.
• A.I. Is a Crapshoot: The Black Hound's an AI-controlled tank that goes rampant, attacking/killing its own Ptolemiac allies in the area before you face it.
• Alien Blood: Mutants and Mars People bleed green fluid while Invader bio-mechanical units have purple blood.
• Alien Invasion:
  • Games 2 and 3, have Rebellion Army teaming up with the Mars People, who intend to conquer earth.
  • Metal Slug 6 has the Invaders, who Came from the Sky on a meteor.
• All There in the Manual: A pretty extreme example, as entire character backstories and various NPC and boss names are mentioned and elaborated upon in supplemental materials, but have absolutely zero presence in the main games themselves and are only relevant to spinoff titles such as Metal Slug Attack, if at all. Perhaps the most notable example is General Morden's motive for betraying and attempting to overthrow the Regular Army: his wife and child were killed in a bombing and he blames the Regular Army for being unable to save them.
• All Your Powers Combined:
  • The final boss of Metal Slug Advance has attacks borrowed from the final bosses of 2/X, 3, and 4.
    • The pods and the Wave-Motion Gun are very similar to the alien mothership's UFO spawn and laser.
    • The attack where it fires out blue shots that arc upwards is like Rootmars' green balls attack.
    • The Reflecting Laser spray is somewhat similar to the one used by Amadeus in 4.
  • Leona's abilities are an amalgamation of all the other characters' abilities.
  • The SV-001 Type-B has the positive traits of the Experimental and the Type-R.
• Always a Bigger Fish: First, the Peregrine Falcons fought the Rebel Army. Then came the Mars People, who proved a bigger threat, enough that the Rebels and the Falcons joined forces against them. Then came the Invaders, who eat Mars People, which led humans and Martians to fight them together.
• Ambidextrous Sprite:
  • Most sprites have their turning animations show their weapons being switched from one side to another. Notably the Slug Gunner swaps its weapons while turning.
  • In the first game, Morden's eyepatch is mistakenly on his left eye despite official art depicting it on his right. Metal Slug 3 turns this into a plot point: the fake Morden reuses the sprites from the first game while the real Morden has new sprites with his eyepatch in the correct position.
• Amen break: "People who had a Hard Time" in Metal Slug 3D, several tracks in 3D and 7 borrowed the elements from the break but played with their own instrument, only the aforementioned track blatantly sampled "Amen, Brothers".
• And Now for Someone Completely Different: The final level in Metal Slug 3 sees the character player one was controlling kidnapped by the Mars People, forcing you to control one of the other 3 protagonists to rescue them for the rest of the stage.
• And Then John Was a Zombie: At level 2 of 3 (and level 4 of 4, if you take the upper path), you can let yourself get infected and turn into a zombie. Although this makes you ridiculously slow, you gain the ability to shoot out a massive blood vomit (which replaces your grenades, and is absurdly powerful even against bosses). The effect ends when you enter the next level, find the medkit item, or die, whichever comes first.
• Animal Mecha:
  • Aeshi Nero from 2/X is a huge mechanical snake-like excavator.
  • Metal Slug 7/XX has a whole collection of them as bosses:
    • The Iron Death Worm, a huge robotic worm that can burrow underground with an equipped drill.
    • Crablops, a crustacean-like mecha that, on an unusual departure from the series is fought two times and the last one can separate its legs and head to attack separately like a Dual Boss.
    • Fall Climber, modeled after a gorilla and a crustacean that follows you up through a waterfall and has a screen covering laser-like Aeshi Nero.
    • The Kraken, whose eight tentacles need to be defeated first in order to challenge the head.
• Animals Not to Scale: After Allen O'Neil is defeated in Metal Slug 2/X, he is eaten by an orca that is MUCH larger than a real one, being so large it eats him in one bite.
• Announcer Chatter: *clickclick* HEAVYYYY MACHINE GUN!
  • RAWKET LAWNCHAIR!
  • SHAWTGUN!
  • WHOA, BIG!
  • MISHOWN COMEPLEET [ending theme]
• Arm Cannon: The LV-Armor fires its equipped weaponry from them.
• Armies Are Evil: General Morden's Rebel Army show up in every game except for 5, and their job is to cause chaos and destruction as payback for the death of Morden's wife and daughter. There are several other, less important armies as well — and you know they're evil because they shoot at you and not Morden's rebels — like the Arabian Infantry (found early on in Metal Slug 2 and Metal Slug X), the Ptolemaic Army (your main opponents in Metal Slug 5), and the Division 6 of the Japonese Army (found only on a secret path in Metal Slug 3).
• Armor-Piercing Attack: Any of the SV-001 type Slugs can acquire Armor Piercing Shells, which do extra damage against enemy tanks, and, most importantly, fly all the way across the screen and are spammable.
• Armored Coffins: There's no way to easily bail out of the SV-000. Either you get out after defeating all enemies or let it explode and kill you.
• Armored But Frail: The Patrol Robot enemy has an armored shell that makes it immune to damage from the back. However, the laser projector in front is a very flimsy weak spot and a few shots there will destroy it.
• Art Shift:
  • While the sprites have a consistent style over each game, the character select screen has different portraits for every game (except for 2/X and 3). This also applies for the promotional art.
  • Metal Slug 7 and its remastered version XX have pre-rendered background instead of being hand drawn unlike the rest of the characters and vehicles.
• Artistic License – Chemistry: In 3D, Eri claims that a sunken ruined city was radiocarbon dated to be 8 billion years old. The writers know how impossible this should be (Marco points out that Earth is only 4.6 billion years old) but that still doesn't account for how the Regular Army was able to pull radiocarbon dating on something older than 50,000 years old.
• Attack Its Weak Point: Required with some bosses, who are vulnerable only in some areas. Including Sol De Rokker (you must shoot the shining pearl on its forehead) and Avatar of Evil (the skull in its chest.)
• Automaton Horse: The SV-Camel is incapable of being hurt. You can't only bring it after the first level of 2 or X, when the SV-Camel will neglect to follow the protagonist to remain near a water source.
• Auto-Scrolling Level: Starting with 3, certain sections of a mission revolve the player flying or driving at a fixed speed. The first half of the final mission of Metal Slug 3 mostly consists of auto-scrollers.
• Autobots, Rock Out!: Metal Slug 5 features a predominantly rock and metal-oriented soundtrack, with a rock version of Final Attack.
• Awesome, but Impractical:
  • The Slug Gunner, a mecha version of the basic tank, looks awesome and is featured in the trailers and cover art. It is also a lot slower than the regular tank- at least while walking. While you can hold down on your control pad to deploy the treads and go faster, its downside is that you can only shoot forward. And it takes forever to turn around.
  • Some of the weapons like the Drop Shot and the Iron Lizard look cool and explode, but the ammunition always drops, preventing you from hitting enemies above you, and aren't much more powerful than the Enemy Chaser or Rocket Launcher.
  • Unlike other Slugs, the LV-Armor requires ammo, can't shoot diagonally (some of them can do the heavy machine gun spreading motion), and takes one full second to jump; all of this makes it a liability at the worst of times.
• Background Boss:
  • Amadeus' final form is a control tower in the background.
  • The Avatar of Evil, the Final Boss of the fifth game, is so large in size that it has to be part of the background to be fought properly.
  • The Kraken, if the fight with its tentacles is not treated as separate battles and is instead the first phase of the Final Battle.
• Backwards-Firing Gun: The SV-001 Type-R and the Slugnoid Type-R (which one you end up with depends on which level route you choose) in the first level of the third game have the unique property of firing in the direction opposite the player points. This is important, since the first boss fight is spent frantically running away from said boss.
• Badass in Distress: Upon beating Morden in Metal Slug 3, he reveals himself to actually be an alien who captured the real General Morden and promptly does the same with the character you are currently playing as, automatically switching you to a different character coming in to save them and Morden. The former character also becomes unselectable whenever you use a continue during the final mission.
• Badass Normal: The main characters are more than capable of taking on zombies, yetis, zombie yetis, aliens, giant robots, UFOs, and everything else with just a pistol, a knife, and some WWII stick grenades.
• Bait-and-Switch Boss: The final boss of Metal Slug 2/Metal Slug X isn't the flying saucer. It is the bigger flying saucer that it becomes part of upon arrival.
• Balloon Belly: Eating too much food will cause your character to become instantly obese (complete with mention from the Announcer). This also makes your shots bigger, and thus more powerful.
• Battleship Raid: The final part of Metal Slug 3 involves an assault on the Mars People's mothership and subsequent raid on the interior of such. One mode lets you play as one of the human mooks.
• Bears Are Bad News:
  • Subverted - the only bear to be found in the entire series is on a secret alternate path in Mission 3 of Metal Slug 4 (a snowy mountain)...and he helps you, attacking the intruding Yeti-like monsters that infest this route. However, you will get killed if you stand in the way of his claws (this uses the same death animation as when the player gets knifed). He will also leave surprisingly docilely if you shoot him a few times.
• Big Bad: General Morden for most of the series. However, other villains such as Rootmars, Amadeus, the Ptolemaic Army, and the Invader King serve as the Big Bad of several installments of the series.
• Big Creepy-Crawlies: Metal Slug 3 in particular has a bunch of these, including locusts, crabs, snails, caterpillars, and Ohmu.
• Big Eater: Nadia is a supermodel who joined the military to burn off all the food she eats, because she can't control her appetite.
• Bigfoot, Sasquatch, and Yeti: Metal Slug 3 and 4 have these. They have a homing ice breath that will not kill the player (unless they are zombified) but turn them into a snowman. If the player can't escape from the snowman fast enough by mashing buttons, the yeti will take out a bone club and whack the player to death.
• Bilingual Bonus: The Arabic writings in the first stages of 2 and X say "Indigestion Restaurent", "Corrupt Bank", and the big banners behind the boss basically say "I have diarrhea, bring me a doctor.".
• Black Comedy: Most of the humor comes from the soldiers’ silliness and the games’ cartoony art style juxtaposed with the graphic scenes of war, death and gore. Especially in the original, which didn't shy away from showing the gruesome results of things like running through a city with a machine gun.
• Body Horror: And lots of it. From tearing enemies to shreds, to being melted or dismembered, this series supplies enough to make most gore fans happy. Also see The Many Deaths of You down below.
• Bloody Murder: When you're zombified, your bomb weapon changes into a massive and extremely powerful stream of bloody puke. This attack is so powerful it can destroy tanks in one use, and it even provides the page image for the trope, no less! The tables turn on you in the final mission of Metal Slug 3, where you have to fight alien zombie clones of your character who also have this attack.
• Boss Banter: Spouted by Allen. "Come on, boy!" "Go home to mommy!"
• Boss Bonanza: The final mission of 3 has a total of SEVEN bosses: Hairbuster Riberts, Hi-Do, Dai-Manji, Rungame, Fake Rootmars, Clone Incubator and Rootmars. Dai-Manji and Rungame in particular are fought back-to-back.
• Boss-Only Level: 3D's final stage is an entire Boss Bonanza of two; the first have you fight the Humongous Mecha Lugus while the second part is Lieu, an SNK Boss Womb Level.
• Bottomless Magazines: Nobody ever needs to reload - but the heroes will reload their pistols if you stop firing after a certain number consecutive shots (9 for the guys' automatic handguns, 6 for the girls' revolvers), just because, though when switching to the handgun in 6, you can't move for a while. The special weapons aren't unlimited, but keep all their ammo in a single magazine. 3D has a system where you can save all your weapons' ammo and use later in certain situations, similar to other Third Person Shooters.
• Bottomless Pits: Occasionally combined with Super Drowning Skills.
• Bowdlerise:
  • Some US home releases of the games replace Tarma's Precision F-Strike death scream with Marco's.
  • The arcade games all have the option to change the blood from red to white...yet the stream of blood you vomit in zombie form remains red no matter what.
• Brain in a Jar:
  • Metal Slug 3's Martian Guards are brains in jars attached to robot bodies.
  • Metal Slug 6's Mission 3 boss is a Humongous Mecha with a brain sitting on top inside a jar to serve as the head. It also has a couple of eyeballs there.
• Brain Monster: 3: Rootmars, the Final Boss, is an alien with a big exposed brain that serves as his weak point. Said brain can occasionally emit a shockwave that is hard to dodge.
• Breakable Power-Up: Characters will lose their current weapon upon death and respawning, except for Leona, who loses her weapons after a continue. Their grenades will also be reset to 10 standard grenades, which is either a power-down or a bonus depending on whether you used up your previous supply or not.
• Breakable Weapons: The Slugnoid loses its cannons when damaged. After taking two hits, it's left without any vulcans and can only use the cannon.
• Bullet Hell: A rare-for-the-time example for a series that isn't (usually) a Shoot 'Em Up - several bosses are known to fire out geometric bullet "curtains" in concentric waves that would be completely at home in said genre.
• Canon Immigrant: After 6 and XX the series has effectively adopted the Ikari Team from The King of Fighters, with Heidern and Whip appearing in Metal Slug Attack because why not complete the set? It’s gotten to the point that in The King Of Fighters XV, the Ikari Team’s stage is Metal Slug themed.
• Captain Ersatz: The Slugs are pretty much their version of Bonaparte.
• Capture and Replicate: Halfway through the final stage in the third game, one of the player characters will get kidnapped by the Mars People. Later, as you storm the Rugname, you find yourself fighting through dozens of clones of the kidnapped character, followed by you finding said character in an aquarium-esque confinement where you have to rescue him/her while more clones attack you en masse. Afterwards, most of the clones turn into significantly more dangerous zombified versions of themselves.
• Car Fu: When you're riding the titular Metal Slug, simply running onto foot soldiers will kill them. You can also send your Slugs (except the animal ones) forward which then self-destructs themselves as you jump out of the Slug.
• Cave Behind the Falls: One inexplicably holds two Slug Mariners in the third stage of 3.
• Climactic Volcano Backdrop: The Final Boss battle of 7/XX is on a Lava Pit inside a volcano.
• Close-Range Combatant: The Ptolemaic Claw Unit is the only Armor to not have any projectiles at all, only using its fists. Conversely, the MG has only guns and no ability to melee.
  • This is Ralf's specialty in 6 and 7/XX. He is the only character capable of using melee attacks on vehicles and even bosses.
• Clown-Car Base: Some of the games from the first onward have its fair share of spawning enemies endlessly until you destroy it.
• Colossus Climb: When fighting bosses on foot, you can actually climb atop some of them to avoid damage. In certain occasions, this is the only way you can damage them or avoid their attacks. Such as the Dragon Nosuke from 2, Jupiter King from 3, Elder Centipede from 6 and The Fall Climber and The Union from 7
• Conspicuous Electric Obstacle: In Mission 2 of the first game, out of nowhere, there are a few electric bolt emitter pairs with electricity constantly going between them. The enemies avoid these by crawling under them.
• Co-Op Multiplayer:
  • Simultaneous two-player is present in the main series except for 7 (it returns in XX).
  • In the mobile game Metal Slug Team Mission, up to four players can play at once.
• Colour-Coded for Your Convenience: A few examples:
  • The Metal Slug Type-R, a faster version of the original tank, is orange instead of gray.
  • In Metal Slug 1 through 3, General Morden's infantry includes Sergeant Rank soldiers, who are identical to any other soldier except for the fact that they wear a yellow uniform and will drop an item for you when killed.
  • Metal Slug 3's Division 6 soldiers come in both olive and red uniforms in order to help the player distinguish which soldiers are going to blow themselves up upon death and, hopefully, avoid their dying attack. It's the red ones.
• Compilation Re-release: Metal Slug Anthology on PlayStation 2, PSP, and Wii collects the first seven games in the series (first game through 6 and X), though it misses the two Neo Geo Pocket games, as well as Metal Slug Advance and Metal Slug 3D, and the games suffer from slowdown.^note which was present in the original releases, but removed when emulating the ROMs with MVSPSP.
• Concept Art Gallery: A whole bunch of it is available in the collection Metal Slug Anthology, which runs the gamut from incredibly detailed drawings of tanks and aircraft to lots of pictures of the female characters.
• Conservation of Ninjutsu: This game practically runs on this trope. One or two people versus entire regiments of both infantry and tanks, as well as alien motherships, zombies, yetis, so on and so forth? No problem. Grab your quarters.
• Construction Vehicle Rampage: The last mission of the first game have Excavator Tanks, which drops steel beams from above the players in an attempt to crush them. There's also the first boss of Metal Slug 6, a powerful, weaponized excavator that attacks the player in an underground cavern.
• Continuing is Painful: You lose whatever weapon you were carrying, your bombs are reset to 10 (although this is helpful if you have used up your previous supply), and your rescued prisoner tally is reset. The blow is slightly softened by the fact that you will get a free Heavy Machine Gun upon continuing.
  • The original Xbox release of Metal Slug 3 took this to an extreme: your continues are limited with no way to continue infinitely like in almost every other console version, and using one of them takes you back to the beginning of the level you are on.
• Continuity Nod: In Stage 4 of Metal Slug 2 and X, there is a movie theatre. In Metal Slug 2, it is showing film 2 of a series; in Metal Slug X it is showing film 3 of the same series.
• Convection, Schmonvection:
  • In 3, the area where you fight Jupiter King is a metal grill right over a pool of molten metal, but the player will only burn if they fall in.
  • In 7, the Final Boss Kraken is fought with the player jumping on metallic scrap pieces floating right on lava, but they're 100% safe from the heat unless they fall in.
• Cool Boat: The Slug Mariner is a small one-seater sub with a high-mass Vulcan and torpedoes that sink to the floor.
• Cool Plane: The Slug Flyer is a hilariously small aircraft that functions just as well as a normal one, and comes with a rapid gun and missiles to boot. It can carry another player or even an SV-001 on top of it without any hindrance in performance.
• Cool Shades: Tarma never takes off his rather expressive sunglasses.
• Cowardly Mooks: Soldiers will freak out if you approach them when they're chatting and not currently attempting to kill you, and some will attempt to run away without even attempting to put up a fight.
• Crapsaccharine World: The world of Metal Slug looks nice and colorful, with tribespeople, animals, and other natural beings living together in forests, cities, and, in some stages, tourist attractions. However, with military and alien influences, things have gone really nasty. Exaggerated, since aliens are even the victims of this.
• Crew of One: All Slugs (except for the Slug Gigant) can be piloted with only one crew. Justified, the vehicles are too small to have multiple crews.
• Crooks Are Better Armed: Zigzagged: your team of mercenaries come with a pistol and supply of small grenades against whole infantries. Even if you can get HEVEE MASHINE GUN or RAWKET LAWNCHAIR and the various Slugs later, your enemies will still have a lot of things under their sleeves. At the same time, though, the infantry's weapons are frequently old, makeshift, or in severe disrepair, and the average foot soldier will have bargain-basement grenades and bolt-action rifles. Death of a Thousand Cuts applies, though, so with enough shootings they'll all fall down.
• Crosshair Aware:
  • The Ten Commandments of Moses from 3 will mark a character's position with a green laser pointer. Seconds later a huge monolith is dropped on the area where the laser stopped.
  • This trope is a common game mechanic for the explosive-based enemy attacks such as homing missiles and bombs in 3D. Prepare to lose one life when you're standing on a crosshair.
• Crossover: Aside from Ralf & Clark and Fio (noted below), Mars People were mid-bosses for SNK vs. Capcom: SVC Chaos and playable in NeoGeo Battle Coliseum alongside Marco Rossi. Not to mention the appearance of the ENTIRE cast on the Card Fighter games.
• Cursed with Awesome: Being turned into a zombie slows you down and restricts you to a pistol...but it gives you a ridiculously powerful attack in which you vomit blood which eradicates everything in front of you. Plus, Rebel soldier weapons are rendered harmless, leaving you vulnerable only to Yetis, other zombies, and bosses.
• Cutscene Incompetence: In 3, after it's revealed that Morden was a fake, the helplessness of Player 1's character when s/he gets abducted is understandable... but not when a Player 2 is there, who just stands there and is not taken too.
• Cutscene Power to the Max: Jumping into the Bradley Slug in4 for the first time has the player automatically turn the Bradley Slug around to face the correct direction, something that would be incredibly useful to do in-game but is impossible to do manually.
• Damn You, Muscle Memory!: Two examples in 5:
  • The slide move, exclusive to this game, is performed by pressing the jump button while holding down. This very same manuever is a common tactic in previous games to shoot enemies underneath you, and players who forget about the slide can potentially be in for a nasty surprise and put themselves in harm's way.
  • The "wind-up" animations soldiers and enemy vehicles telegraph their attacks with have been changed and require different timing to avoid, presumably to throw off veterans who had enemy behavior hard-coded into their brains across the previous four games.
• Dance Party Ending: Completing the original Metal Slug with two players foregoes the usual sad and bittersweet ending of your wiping out the Rebel Army in favor of a more upbeat song and seeing the army go through their various animations to "dance" to the credits theme all along the way.
• Darker and Edgier:
  • Metal Slug 5 eschews most of the comical parts of the series and plays it almost completely straight-faced. Morden, Allen, and the Rebel Army are Put on a Bus and replaced with a much different group of enemies ranging from veiled terrorists to armed mecha. As a result, the game feels far less humorous than its predecessors, aside from the ability to turn fat in the first mission. However, most of the new enemies are edited from Rebel soldier sprites and share their idiosyncratic and occasionally casual behavior. The game also features a more heavy metal-induced soundtrack in comparison to the previous games.
  • Metal Slug 6 as well, albeit to a much lesser degree. For example, the game features Marco and his team joining forces with both the Rebel Army and the Mars People fighting against a new, dangerous threat that not even the Mars People themselves can handle. Additionally, this game dropped the concept of character transformations, and they did not return for 7 either.
• Dating Sim: The Combat School extras on the home releases (often in Japanese) has elements of this. The instructors will warm up to you the better you perform in this mode, and will chew you out if you screw up. Eventually, if your rank is especially high, you can chat with the instructor and get to know a little more about her. Good luck understanding Sophia in Metal Slug 1, though.
• David Versus Goliath: Almost every boss fight in the game consists of your player character (or your player character in a hilariously small vehicle) against a behemoth of a boss. Of note:
  • The fight between Slug Flyer and the Dragon Nosuke has the Flyer smaller than the Dragon Nosuke's "head".
  • The fight between Slug Flyer and Shooting Ray in 5 shows that the Flyer is barely the size of a single-engine of the Shooting Ray.
• A Day in the Limelight: Present in the cellphone games in which the player can only control one character, most notably Metal Slug Mobile 3 in which you can play as Allen O'Neil.
• Death Is a Slap on the Wrist: It's an arcade game, so you respawn where you died within a couple of seconds. A lot of the console versions have infinite continues to boot, though 3's Xbox port is a jarring aversion, as using one of your very finite continues makes you restart the whole level, rendering the final mission an utter nightmare. Regardless of which game and version you're playing, dying does erase your entire "POWs rescued" list, so if you're gunning for a high score, one death at the stage boss can completely break your run.
• Death of a Thousand Cuts: Even the most badass tank will go down if you shoot it enough with your pistol.
• Degraded Boss:
  • Shoe and Karn were dual bosses in the first game, and individuals of them show up in later levels of 1 and 2.
  • Hairbuster Riberts from 1 is a midboss in the 3rd.
  • The final bosses of 1 and 2 also become midbosses in 3.
• Denial of Diagonal Attack:
  • Most weapons, though the Heavy Machine Gun and (as of 6) the Laser Gun will let you briefly shoot diagonally as you switch from horizontal to vertical fire or vice-versa.
  • While the SV-Camel and Ostrich Slug cannon can fire in all directions, it can't turn around. So you will only be able to throw grenades forward while on it.
  • The LV-Armor has a major deficiency in its ability to shoot diagonally, which even applies to heavy machine gun ammo.
• Denser and Wackier: The first game only had occasional moments of humor, gave off the atmosphere of a WWII-style Dieselpunk game (albeit actually being set in 2028), and featured an outright depressing credits sequence when finished with only one player. The second leaned hard into the cartoony animations, made the violence much harder to take seriously, introduced far more outlandish locations, enemies, and weapons, and the rest is history.
• Depending on the Artist: The series has had multiple people providing concept artwork for it since its inception, and has no consistent style. This has resulted in in-game and promotional artwork run the gamut from being cutesy and Animesque, to gritty and realistic, to cartoonishly surreal, to outright disturbing. Just compare Marco's appearance in the first game to his appearance in X or his appearance in 5.
• Destroy the Security Camera: From 3 onwards, surveillance cameras with machine guns attached to their sides are a recurring threat for infiltration-based missions. However the cameras can be shot from a distance and is easily destroyed, even with handguns.
• Detachment Combat: In 7, Crablops does this the second time it's faced, separating into head and body that attack simultaneously and have to be taken down separately.
• Devolution Device: The scientist enemies in 4 fire darts that turn the player into a monkey (who reuses sprites of the monkey prisoner Utan from 3) if they hit, and can also attack with a syringe at melee range that has the same effect. The transformed player's weapon also changes into the same Uzi that Utan uses. If the player dodges the scientists' melee attack, they'll stab themselves with their own syringe and turn into a different monkey that can be collected for points.
• Difficulty Levels:
  • Metal Slug 1 to 5 share a similar difficulty system to other SNK arcade games, changing the level number in the range of 1/Very Easy to 8/Very Hard.
  • Metal Slug 6 uses two separate difficulties: one similar to the previous games and a second where the player can use an infinite Heavy Machine Gun (Easy) or a pistol with the ammo cut in half (Hard).
  • Metal Slug 7/XX uses one simpler system: Beginner, Normal, and Hard. Beginner differs from the latter two as the player is given an infinite Heavy Machine Gun and ammo is doubled.
• Diligent Draft Animal: In Metal Slug 6, a new unit in the second level is called the Donkey Slug, which serves as a steed to players. The donkey will give the player a lift for miles from early in the level to the boss' arena, while carrying a mini-gun containing thousands of rounds, and even willingly pulls behind a donkey cart mounted with a Vulcan cannon while carrying its owner.
• Divergent Character Evolution:
  • The fourth game: Trevor's melee attack earns extra points but briefly renders him unable to move when he uses it. He's kicking the enemy hard enough to shred them apart. Nadia, on the other hand, whips out a taser and, strangely, only earns 100 points as opposed to the 500 all other characters get. Although this is likely a programming oversight, it is retained in all console ports.
  • The sixth game introduced differences between the characters. Marco's normal handgun does more damage. Eri gets more grenades from pick-ups and can throw them at any angle. Tarma gets more hit points when piloting a vehicle, and can lock the vehicle's gun in one position while moving. Fio receives more ammunition from special gun pick-ups and starts each life with a Heavy Machine Gun (or the Big equivalent on Easy mode). Ralf can take two hits before dying, and has a special melee move called the "Vulcan Punch". (To compensate, he receives half the normal amount of ammo and grenades from pick-ups.) Clark has a special move called the Super Argentinian Backbreaker which kills any man-sized enemy in one hit, makes him temporarily invincible and earns him a large stack of points the more he combos it.
  • In XX, Leona has an amalgamation of the main team's skillset (stronger pistol, 20% more ammo and grenades, Slugs can take an extra hit, and her special melee acts like a short-range Zantetsu Sword). Marco also got the Burst Fire, which lets him use auto-fire, but has to stand still, and Tarma can kick Slugs, which can recover some health (however, it can also damage them on occasion.)
• Double Jump: The LV-Armor, Slug Gunner and Slug Armor are capable of using a Jump Jet Pack if it jumps in midair.
• The Dragon: Allen O'Neil. However, during the joint strike on the Martian ship, he helps the player a few times. He's trying to rescue his general, after all.
• Dual Boss:
  • Shoe & Karn from the first game, two tanks that attack from each side on a different elevation.
  • The Mammoth Tower from 5, two mechanical elephant heads controlled by two Ptolemaic cult members that fire maggots as well as attacking with their trunks.
  • Crablops from 7. The second time you fight it, it detaches its head from its legs, and you need to destroy both separately.
  • Subverted by Emain Macha from Advance, despite being called The Twins, you only fight one at a time.
• Early-Installment Weirdness:
  • There are a number of things from the first Metal Slug game that seem strange in retrospect:
    • The only playable characters present are Marco and Tarma, and there is no character select screen — Marco is automatically assigned to player 1 and Tarma to player 2. They do not strike a victory pose at the end of a mission.
    • The game's tone is fairly grounded, and the humor and cartoony elements made famous in subsequent games is more subdued here. The depressing ending after finishing the game with one player in particular would feel very out of place after the first entry. To wit, there are no transformations nor any supernatural elements to speak of.
    • The only weapons besides the pistol are the Heavy Machine Gun, Flame Shot, Rocket Launcher, and Shotgun. The brief diagonal firing that the Heavy Machine Gun does when switching directions is more finicky and unreliable to pull off here. The Flame Shot shoots out a weak fireball that travels far across the screen, as opposed to the shorter-range but incredibly powerful Flame Shot of later entries, and there is also an alternate "burning" animation for the enemies where only the top half of them catches on fire rather than their whole bodies (the flames also look quite different from the other animation) that is only used in the first game and never again.
    • The grenades fly at a slightly shorter range and are tinged red. Mooks hit by grenades also turns sandy-brown when blown up (the same death animation plays if an exploding Metal Slug happens to catch enemy soldiers in the way).
    • The franchise's iconic "Boss Theme", "Steel Beast", was played in the middle of the second stage, during the Mini-Bata battle. Stages in future entries featuring said song will play it exclusively at the end of a stage when the player takes on a boss, giving Mini-Bata the honor as the only Mini-Boss granted said theme.
    • The equally-iconic score, "Assault", made its debut in the latter half of the original game's second stage (after the aforementioned Mini-Bata mid-boss), lasts until the Hairbuster Riberts boss and somehow continues playing in the third stage. Later entries will play a different score by default every new stage.
    • Another music-related oddity, "Final Attack" (the score that always plays in final missions) was used in the first half of the last stage, before it's usurped by the aforementioned "Assault" all the way to the stage's end. All later installments featuring said theme ^note save for 4 where it's absent and 6 where it plays only for 5 seconds at the start will use it as background music for facing the Final Boss.
    • Allan O'Neil is fought in the third stage, while future games will feature O'Neil as a mid-boss of the final mission. Additionally, after defeating Allan O'Neil, you're unable to claim O'Neil's machine-gun for yourself, for no given reason. This is changed in later games where O'Neil's dropped weapon can be collected (equivalent to a fresh Heavy Machine Gun pickup).
    • The voice of the announcer is different; he's also present in 2 before his better known, hammier replacement debuted in X. His "Mission Complete!" voice clip doesn't play until the "Mission Complete" text has already appeared, rather than immediately after the prisoner tally.
    • The only usable vehicle is the Metal Slug, although the player can use a turret on the battleship in the final mission.
    • It is possible to bring a Metal Slug vehicle to each boss fight, a privilege subsequent games do not always grant you. To get bonus points for the Metal Slug, the player simply needs to bring the tank to the boss arena and keep it intact until the mission ends. Later games add the requirement the player to be on a slug during the boss' defeat animation in order to receive credit, and doing the final blow on foot won't count.
    • You can throw grenades out of the Slug's cockpit while crouching, but you can't collect them — picking up Bomb crates while riding a Slug always gives you cannon ammo, and you have to get out and pick them up on foot if you want grenades instead. Starting in X, picking up Bomb crates with the Slug in "crouch mode" gives you grenades, allowing you to choose which explosives you get. Also, you can actually throw grenades faster when using the Slug than when on foot—later games nerfed this so that you throw them at the same rate whether in a vehicle or not.
    • The health of the Metal Slug itself isn't fixed to a three-hitpoints system. It is possible to take less or more damage than 1 unit of hitpoint depending on the specific attack of the enemy.
    • In later levels, enemy soldiers will jump onto the Metal Slug while the player is using it and attempt to either destroy your vulcan cannon with a hammer (the Metal Slug cannot lose its vulcan cannon in any other game, although this idea was carried over to the Slugnoid from 2 onwards), attempt to climb and open the hatch of the Metal Slug and throw in a grenade (which will damage the Slug and not the player), or mount in front of the main cannon to block the cannon projectile from launching, forcing players to spend and waste three cannon shots to dislodge said rebel! This behavior is not present in any subsequent game.
    • While riding the Metal Slug, the "ARMS" counter in the HUD will still show your ammo count for your current special weapon, if you have one. In later games, the "ARMS" counter changes to the infinity symbol for the Slug's vulcan gun.
    • The rescued prisoner list uses a different font, namely the same one used for the 1UP and ammo count.
    • The Eaca-B and the Flying Tara (which are palette swaps of an otherwise identical plane sprite) behave distinctly from one another: the latter will fly from the background first before showing up and drop air-to-ground HE bombs, leave and repeat, while the former will always show up and launch missiles from its bottom hatch before leaving the field for good. In 2 and onwards, the Flying Tara behaves identically to the Eaca-B.
    • The jump physics of the player character is higher and much floatier and a lot more sensitive (Think Luigi instead of Mario).
    • Thematically, the first game is also notable for its lack of weirdness. No Mars people, mummies, zombies, lasers, Iron Lizards, or any stuff like that. Just a straight-up war story. It is also surprisingly less violent than later entries.
  • Metal Slug 2 isn't immune to this either, and it's particularly pronounced if you go back to it after playing X:
    • The announcer (the same one from the first game) does not say the name of the character you choose at the beginning, and the "WHOA, BIG" voice clip normally heard upon becoming fat is absent here.
    • Fio's death scream is the same as Eri's, and her victory animation is missing the part where she gives a "V for victory" sign.
    • The Camel Slug's bullets are identical to the Metal Slug's in 2, but were changed to larger oval-shaped bullets in X.
    • The Slug Flyer's first appearance is in a stage that can be traversed perfectly fine on foot. Subsequent games would relegate the Flyer to dedicated Shoot 'Em Up sections. As with the Camel Slug, its bullets are identical to the Metal Slug's in both 2 and X and were eventually changed to small lemon-shaped projectiles in 3.
    • The Heavy Machine Gun cannot be fired diagonally while fat in 2. This is particularly jarring since the segment in mission 4 in X where the UFOs show up practically requires you to take advantage of both fat mode and diagonal HMG fire.
    • Numerous enemies were introduced in X and are not present in 2; namely the mummy dogs and moth mummies in mission 2, the motorcycle soldiers in mission 4, and the white aliens in the final mission.
    • X also introduced several new weapons, and their absence in 2 is definitely felt (to put it in perspective, X has almost twice as many weapons as 2, not counting the "big" variants), especially since 2 has a disproportionately high amount of Heavy Machine Gun drops at the expense of the other weapons.
  • When the Two Machine Guns were first introduced in 4, the weapon is treated as a "penetration" type weapon as shown where Rebels died in a rather gruesome manner if used on them. This particular damage-type does not return in 5 and onwards, where the the 2MG is treated as a "normal" type weapon instead. This behavior also applied to the Rocket Launcher in the first game before being changed in 2.
• Easy-Mode Mockery:
  • Playing Metal Slug 6 on Easy ends the game on the fourth mission.
  • In Metal Slug 7/XX, playing on Beginner or Normal does not show the unique Mission All Over screen, rather just showing the normal one seen in previous games.
• Eldritch Abomination: Avatar of Evil in 5, the Invader King in 6, Lugus and Lieu in Metal Slug 3D.
• Elevator Action Sequence: Happens in 3 and 4 and done in reverse in 5.
• Elite Mook
  • The Sergeants are an uncommon Rebel foot soldier, and they wear yellow. They are just as weak as the normal soldiers, but they always drop a pickup when killed.
  • The Amadeus Infantry in Metal Slug 4 are among the most dangerous Rebel foot-soldiers, and they wear blue. Some of them are armed with the 7.62mm AR-10 Autorifle (The real name for the Heavy Machine Gun).
  • Ptolemaic Officers wear grey uniforms and don't cover their faces like the other soldiers. They can shoot their pistols in any direction and can take an unusual amount of damage for a human enemy, but they will run if their troops are killed.
  • The Ptolemaic Special Forces fight like an improved form of the standard Ptolemaic guerrilla. They tend to ambush you out of doors and elevators, and they can even throw knives.
  • Ptolemaic Cultists can take more than one attack and can fire green, homing projectiles.
  • The red Invader drones can take far more damage than the average Invader drones and tend to bounce around the area while spinning.
• Elite Zombie: A few of them appear in the zombie-based levels:
  • Standard zombies are "vomit zombies" whose Zombie Puke Attack will zombify survivors as well as the player characters. Among them are fat zombies that are incredibly resilient, to the point that they can tank a grenade or two.
  • Zombie Rebel soldiers are really resilient, sightly faster than the other undead, and attack with a Deadly Lunge that ends in them exploding into infectious vomit.
  • Tar Men (named and modeled after the infamous sludge corpse from The Return of the Living Dead) are the most elite infectious zombie type, they attack faster and are often found in trickier situations that makes them harder to kill. Finally, they throw a huge arc spray of vomit compared to single globs.
  • The player characters themselves count too if they get zombified. Firstly they stay as smart zombies, retaining their sentience and can fully act under player control (albeit with only standard pistol, no melee attack, crouch, and a very low jump), secondly they become completely immune to conventional damage (but zombifying fluids and boss attacks will kill them), and last but not least, their "bomb" button makes them vomit up a sweeping devastating stream of blood that destroys pretty much any non-boss enemy instantly.
  • Finally, the most deadly enemy zombie type in the game are the Alien Zombie Clones of the player characters, only found in the final part of the final level. They have a massive amount of health, and they use the same blood vomit sweep that the player characters had as zombies (which doesn't turn player characters into zombies, it just kills/damages and is difficult to avoid).
• Emergency Trainee Battle Deployment: In Metal Slug Advance, two young trainees of the Peregrine Falcon mercenaries had to be dispatched because the Rebel Army struck during their training session.
• Emergency Weapon: The pistol and the knife. Depending on the circumstances, other emergency attacks include kicks, nightsticks, hand-axes, tridents, sporks, using your belt as a whip while fat (or stabbing them with a giant fork), and the old telescopic-boxing-glove gag (for the male characters).
• Enemy Mine: Statistically speaking, the Rebel Army is the king of this trope. They only truly appear in the first, second, third, and sixth Metal Slugs, and out of those four, they team up with the heroes in three.
  • In Metal Slug 2 their Martian allies betray them and kidnap their leader, causing the mooks to join forces with the heroes.
  • In Metal Slug 3 their leader was kidnapped and replaced by a disguised Martian, and after they figure this out, they join the heroes in their Battleship Raid of the Martians' Mothership.
  • Played with in Metal Slug 6; they team up with the Martians again, but a new alien species (Invaders) finds Earth right after Mission 2 and find it ripe for the conquering. As for the favorite food of these aliens? Mars People. So now you, Morden's army, and the Martians all team up against these new baddies.
• Episode of the Dead: In the third game, the second level has you fight zombified people, and later, zombified soldiers of the Rebel Army. The reason for the zombie phenomenon is tied to the level's boss: an alien artifact (and the aliens that guard it) mutating civilians. The zombies return in the fourth level of the fourth game, with no explanation other than that the "hazmat" soldiers in the same level were evidently responsible.
• Escape Pod: The SV-001 Slugs are equipped with a floatation device, which is buoyant enough that the player can survive falling from space with it.
• Escort Mission: If you rescue Hyakutaro Ichimonji or Utan and then finish the rest of the mission without dying (as doing so causes them to flee), you'll get a big point bonus for having them with you.
• Evil Is Bigger:
  • Allen O'Neil is much bigger and more muscular than the player characters.
  • Metal Rear, the first boss of Metal Slug 5 is a far larger Evil Knockoff of a Metal Slug. You're even able to bring your own Metal Slug to fight it.
• Evil Knockoff:
  • The Ptolemaic Army from Metal Slug 5 stole the blueprints of the titular tanks which allowed them to create their own bastardized Metal Slugs. In fact, the first boss is a titanic Metal Slug dubbed Metal Rear. According to Metal Slug Defense, they also seemed to have stolen blueprints of the Rebel Army's vehicles.
  • Similarly, the first boss of Metal Slug Advance for the Game Boy Advance is Formor, a roughly twice-as-large version of the Metal Slug.
• Evil Laugh: General Morden, Allen O'Neil, Rootmars, and Amadeus.
• Evil Overlooker: In an unlockable background in Metal Slug Anthology.
• Exclusive Enemy Equipment: Played straight with most enemy weaponry and equipment except the LV-Armor, the Rebel Army's version of the "Slugnoid", that can be hijacked by the player after killing the LV-Armor pilots.
• Expressive Mask: Tarma in XX, and also the tribesmen in 5, with their giant masks that laugh when they laugh.
• Family-Unfriendly Death: It's a game with a cartoony art style, and it has lots of blood, and people die in surprisingly disturbing ways. Noteworthy samples are:
  • Whenever a Rebel soldier gets killed by a "penetration" attack, they are dismembered, maimed, and beheaded. The console versions of 1 and X omit this gruesome animation (and in the latter, the disintegration animation is used, though their corpse afterwards is still there).
  • The Arabian enemies in Mission 1 of Metal Slug 2/X die in conspicuously more violent ways than the Rebel soldiers. The Arabian Soldiers can gorily disintegrate or spew out blood as they drop dead, and the Arabian Fighters will usually explode into severed heads and limbs.
  • During the Iceman route in Mission 2 of Metal Slug 3, after going the end area where you can liberate an Elephant Slug to aid you and go back, you will encounter bodies of Yetis who are killed in a surprisingly graphic fashion, courtesy of the zombies suddenly swarming in.
  • In the Division 6 route in 3's fourth mission, if a Division 6 fighter pilot rams a wall their plane gets crushed along with the pilot, complete with a gruesomely detailed animation of their death.
• Fake Longevity:
  • Done intentionally with Metal Slug 3's final mission. It takes an autoscroller to reach the first boss, another to reach the Rugname (the second boss), and then another just to traverse a freakishly long tunnel within the spaceship. This whole ordeal takes about a third of the game's length, possibly longer than the previous missions combined. The proper on-foot section of the mission (the last third) is just a few minutes longer than any other final mission and just as long as Metal Slug 6's final mission. There is also no port that splits the final mission, so all of it has to be done in one go.
  • The Mummy path in mission 4 of Metal Slug 4 leads to an enclosed room having the player fending off mummies and hazmat soldiers. If done quickly, it will take around three minutes to leave said area, and there is more left to traverse after that. The Zombie path, in contrast, has no equivalent and is thus a far shorter path.
• Fan Remake:
  • A group known as AA Productions have set up a remake of the fifth game known only as 5 Elite, boasting true-to-arcade visuals and production values.
  • Also, SB Fanthology
• Fanservice: Metal Slug Anthology has a picture pack which includes lots of pictures of the female characters. In addition, when the female characters are killed, they sometimes suffer Clothing Damage to a degree the male characters do not - for example, the giant snail acid in 3 will instantly make a male character turn green and collapse into a puddle of ooze, whereas the female characters will have their clothes melt as they sink to their knees before keeling over, giving you a good eyeful.
• Fanservice Pack: Poor Fio just won't stop gaining weight from one game to the next.
• Fire-Breathing Diner: The Elephant Slug gains the ability to shoot fireballs by picking up a hot pepper.
• Fire, Ice, Lightning: The three coloured flying pod enemies in 7/XX will harm the player character differently on contact. Orange ones burn the player character, blue ones turn them into a snowman, and yellow ones electrocute them.
• Flaming Meteor: Played with the Monoliths, which are unlockable bombs in 3D. These alien monoliths don't appear to be engulfed in flames, until it hits the target of course.
• Flanderization: The gameplay behavior of an enemy, specifically the Bull Chan, of all things: In 1, they fire from cliffs and only fell down when the edge of the cliff supporting the tank is destroyed; any Bull Chans that show up from the same destroyed cliff will only attempt to plummet down if their target is below them. A similar behavior was adopted in X when the Keesi acted as a mini-boss, though they may do so at will, either immediately or after firing a few rounds. However, in 3 and 7/XX, they are only known for their one characteristic, falling and crashing down.
• Flash of Pain: For an example, an orange variety is found in the first Metal Slug.
• Fluffy the Terrible: The giant eels from 3, named Helen, Linda, Jenny and Barbie.
• Flying Seafood Special: Flying Killers from 3 and 6 are piranha-like fish that jump out of the water, then fly straight at you.
• Foreshadowing: Whether due to a glitch or something intentional, after Morden hits the ground with an excess blood splatter in the first game, you can attack his "body" as he continues grunting like an injured enemy despite the supposed death. Naturally he gets an Unexplained Recovery for the sequel, and with almost every other game that seems like it kills him again.
• Fragile Speedster: The SV-Camel and the Ostrich Slug are faster than the other tanks, and faster than the player when running. However, outside of elevating the player above low-ground attacks, they offer no protection.
• Food Chain of Evil: The Invaders in 6 eat Mars People. It gets bad enough that the Mars People and the Rebel Army team up with you to take them on!
• Gasmask Mooks: The Ptolemaic Special Forces.
• Gatling Good:
  • See image at top of the page. Some enemy soldiers wield them, for what good it does.
  • One of the Slug Gunner's arms is equipped with a gatling gun.
• Giant Enemy Crab: Metal Slug 3's first mission is full of giant crabs, with a truly enormous one serving as the boss. Take the right alternate route in the fourth level and you'll find some more.
• Giant Mook:
  • The Ohumein-Congas from Metal Slug 3 are giant-sized versions of the Chowmein-Conga, which absorbs a lot more damage than their smaller brethrens.
  • From the same game, the Mars Mecha from the final stage are giant-sized Hopper Mechas.
  • Metal Slug 6 has the Hunter Lord, absolutely humongous versions of the Hunter Walker.
• Giant Space Flea from Nowhere:
  • The Avatar of Evil, the final boss of the fifth game. After facing hordes of terrorists, robots, and cultists, you're greeted by a giant demonic entity on the top of a tower. Only thing remotely connected is a single cutscene at the very beginning of the game, and that's it (there were supposed to be more cutscenes that would flesh it all out, but they were left on the cutting room floor).
  • Metal Slug 3 has no mention of Mars people before they reveal themselves, however, they are not a complete surprise to the watchful eye. Morden has his eyepatch on the wrong eye, and a few Martians appear in the background of the first level. They were also an important part of the story in the second game.
  • Sol Dae Rokker from Metal Slug 3 plays this straight, being some sort of deity that has no connection to Rebellion Army or Mars people.
• Glass Cannon:
  • While the Slugnoid has two turrets and therefore twice the firepower of most Slugs, it will lose a turret upon getting hit, and will only be able to use its cannon after two hits.
  • The Bradley Slug's missiles are very powerful and useful, but due to a bug, it does not undergo Mercy Invincibility after getting hit like every other vehicle does, making it extremely vulnerable to any enemy that fires multiple projectiles at a time like a Di-Cokka or an MH-6S Masknell.
• Gone Horribly Wrong: Those weird mutants in 2 and X? Turns out they're the leftovers from a Super-Soldier project.
• Good Colors, Evil Colors: The Bradley Slug is bright green to represent the Regular Army, as opposed to the grey/dark green of the bad guys Bradley.
• Goofy Print Underwear:
  • The POWs dispense Power Ups from giant pairs of blue-and-white-striped boxer shorts.
  • When the Mars People turn on General Morden in Metal Slug 3, they strip him to his polka-dot boxers. (When the same thing happened in Metal Slug 2/X, he was wearing pink bikini briefs.)
• Gross-Up Close-Up: The character selection portraits in 2/X and 3. For bonus points, if you choose Tarma, a drop of snot will come down from his nose.
• The Ground Is Lava: The final boss of 7/XX is fought in a huge smelting vat made out of the caldera of an extinct volcano, while your character jumps from platform to platform. If you touch the molten metal, you burst into flames and die. It has several moves that involve taking away a few platforms, or dragging them into its milling machinery (mounted on the outside of the Iron Death Worm it's using as Combat Tentacles) to destroy them—and you.
• Guide Dang It!: Certain items and POWs can be only found by shooting at background objects or at thin air. This would not be a problem except when going for high scores or for the Combat School missions that require the player to collect all POWs or items in a mission.
• Guest Fighter:
  • Ralf and Clark are playable in Metal Slug 6. Returning the favor, Fio is unlockable in The King of Fighters: Maximum Impact 2.
    • Since Ralf and Clark returned in 7, it seems likely that they're here to stay.
  • Marco Rossi also appeared in NeoGeo Battle Coliseum as a playable character.
  • XX (The PSP version of 7) added Leona. She previously appeared in the cellphone games.
  • Awakening (the 2023 mobile game), as a collaboration with Tencent Games, features one gun-toting heroes from their MOBA games each: Alessio and Violet.
• Guns Akimbo: Metal Slug 4 introduces the TWO MACHINEGUN! (2H) weapon powerup.
• Harmless Freezing: Getting hit by Yeti ice breath or blue floating pods will turn the player into a snowman. While this doesn't kill the player, they become immobile and a sitting duck for enemy attacks until they break out of the snow.
• Hand Blast: The LV-Armor appears to fire its weaponry from its palms/claws.
• Heroic Willpower: Probably the reason why your characters still retain their minds/sentience when turned into a Mummy or Zombie, while other infected humans become mindless monsters that immediately attack you on sight.
• High-Pressure Blood:
  • Mooks leave a quite respectable trail of blood upon being shot or cut. Shooting down a Mook with the Shotgun results in them emitting a massive burst of blood that is twice the size of their regular sprite.
  • Weaponized by the zombie versions of the player characters, where the grenade attack is changed to a sandblaster-like jet of blood.
• Hijacked by Ganon: Inverted in Metal Slug 4. What appears to be Allen O'Neil and General Morden are actually look-alike robots manufactured by a new enemy named Amadeus.
• Homing Projectile:
  • The rebel forces sometimes have access to turrets, as well as the T-2B Melty Honey, that can fire slow-moving missiles which homes in on the players, although those missiles can be destroyed before hitting their targets.
  • For the players, there is the Enemy Chaser, which fires homing missiles that targets the nearest enemies, useful in getting players out of tricky situations. The rockets from the Rocket Launcher also attempt to home in on enemies, but aren't as reliable.
  • The Slug Flyer's missiles orient themselves slightly on their own.
  • The Black Hound uses this when it becomes playable in Advance. A rapid-fire version of it, too.
• How Do I Shot Web?: Despite the Bradley Slug being found in the hands of Rebels (who were formerly a part of the Regular Army), they don't have any idea how to work its Vulcan cannon or its jumping ability, only knowing how to operate its indirect missile fire like their standard Bradleys.
• Humongous Mecha:
  • The third boss in the third game is a nuclear-powered giant robot that attacks by dropping rockets and firing Eye Beams.
  • In one mission on XX, you get to pilot one near the end of the mission. And you get to fight Allen in a similar mecha as well.
• Hyperspace Arsenal: One miniboss from X (which was also the first boss in Metal Slug 2) is a super-heavy assault plane that carries those huge tanks that drop themselves on you when they run out of ammo. It carries an infinite supply.
• I Have a Family:
  • Although Allen O'Neil himself doesn't invoke this in-game, supplemental material says he has a wife and son. This is what apparently gives him Contractual Immortality. His son shows up to fight you in the final mission of Advance if you choose the right path, however.
  • General Morden had a wife and daughter who unfortunately died in a terrorist attack at Central Park. When he found out the attack could have easily been prevented if not for the high amount of corruption in the military and government, he betrayed the Regular Army and started the Rebel Army.
• Identical Stranger: The NPC businessman (called Duke Koudou) encountered in 2's first mission has an uncanny resemblance to Amadeus, mentioned above.
• Idiot Ball: One of the most egregious examples during the climax of 3. After the reveal that the Morden you have been fighting is a fake, the player character gets captured which forces you to change to another character. There is a section later on that requires saving the captured player character, so you can't save him/her. However, if you are currently playing a two-player game, you would think having a second player character would mean that the Martians would kidnap the second player character as well if that was the case, as you have four characters in total to choose from so there shouldn't be any worry regarding replacements. Instead, they just kidnap player one's character while player two's character just stands there instead of trying to save his/her teammate.
• I'm a Humanitarian: Implied. If an Arabian Fighter gets gibbed there is a chance that they will drop a meat, sometimes more than one, implying that these are their remains and the players can eat them, via collecting them, for points.
• Implacable Man: Allen O'Neil, Morden's bodyguard who soaks more damage than most tanks, and manages to come back from the dead an unnerving amount of times. In Metal Slug 2, he actually gets eaten by a killer whale which even spits out his bones afterward..? And yet, in Metal Slug 3 he's there again, taunts and all, and he amazes us even more by coming back from the dead again and helping you in the endgame. Although he took a vacation after 3, not appearing for a few games (the one in Metal Slug 4 is actually a robot), he returns in Metal Slug 7.
• Improbable Weapon User: When in fat mode, your melee weapon (a combat knife or hatchet) is replaced with a really big spork or, if you are crouching, your character's belt.
• In a Single Bound: The Slugnoid's specialty is its high-jumping capability, as it was designed for mountainous terrain. This is improved even more for the Slugnoid Type-B, who can jump to even greater heights.
• Incredibly Durable Enemies: Most of the non-human mooks, which Metal Slug 3 and 6 feature an abundance of them.
• Inertia Is a Cruel Mistress: The Slug Mariner uses high-mass rounds that are affected by gravity, putting it at a disadvantage when firing at an enemy above it.
• Infinity +1 Sword: The Slug Gunner of Metal Slug 3D appears when you assemble all Gunner parts onto your Slug, however, by the time when you assembled it, you have already cleared all missions with all 4 characters ^note Only Mission 1-3 and 9 are different for each character, the rest are the same.
• Instant Ice: Just Add Cold!:
  • If you fall into the water in Metal Slug 2/X's final mission, your character dies and floats up as an iceblock.
  • Getting hit by a Yeti's homing frost breath in 3 or 4 or a blue flying pod in 7/XX will make the character turn into an immobile snowman. They can thankfully escape from this.
• Instant Illness: Any player or injured civilian getting hit by infectious zombie fluids dies immediately, gets struck by a lightning bolt, then rises up as a zombie, all in less than 5 seconds. The inverse is even faster- any zombified player that touches a medkit instantly turns back to human.
• Interquel: Word of God states that 6 takes place between 3 and 4 while 7 takes place between 3D and 5.
• Invulnerable Civilians:
  • Most civilians in the background are immune to damage and harm and are ignored by enemies.
  • In Metal Slug 2/X, the first stage contains a baby crawling around. Like most civilians, they're immune to damage but they can get tossed around by explosive weapons. They'll just get back up no worse for the wear.
• Item Amplifier: On 6 onward, certain characters will gain more for certain items on pickup.
• Jack of All Stats: Other than the addition of a new move, Clark plays just like the characters from 1 to 5.
• Japanese Ranguage: The XX announcer generally has better pronunciation than his predecessors, with the conspicuous exception of "Frameshot".
• Jet Pack: Your character gets one of these in the beginning of 3's final mission, where in case the Slug Flyer / Copter gets destroyed, they will rely on their jetpacks instead. Said jetpack also contains its own built-in rocket launchers in place of the player's grenades. The same jetpack is used during the mission 2 boss battle of 5, if the player's Slug Flyer loses to the Shooting Ray during the aerial combat. It makes another appearance in one of mission 4's routes in 6, specifically the one with the Slug Flyer, also in case the Flyer gets destroyed while in flight.
• Jump Jetpack:
  • The Slugnoid high jumps are jetpack-assisted.
  • The LV-Armor Double Jumps are jetpack-assisted.
  • The Bradley Slug jumps with the help of a thruster beneath its treads.
  • Most kinds of Slug Gunner and Armor can use rockets to boost themselves once in the air.
• Just Train Wrong: The entirety of Mission 3 of Metal Slug 2/X. Multiple trains follow each other in sort of a convoy with little gaps between them, which would spell disaster once any of the trains needed to apply brakes. The rhytm of the "cluckety-clunk" sound remains the same throughout the entire level regardless of whether the cars have bogeys or single wheel sets.
• Kamehame Hadoken: Hyakutaro (who disguised himself as a POW) will stick by you after being rescued, firing ki attacks from their palms to kill enemies until you either die or move to the next area.
• Kaizo Trap: Whenever a boss is killed, all their attacks blow up together with them. However...
  • The final mission of Metal Slug 4 subverts it, where after the boss is defeated, the entire base starts collapsing and your player will have to flee before the building goes down. If you escape, you're treated to the Good Ending; but if you lose, you get the Hospital Epilogue ending instead.
  • Played straight in the final level of Metal Slug 6. After being defeated, the Invader King attempts to drag the players down with him to their deaths by collapsing the entire lair and firing his attacks all over the screen. The King goes out in a fiery explosion, but if the player survives his attacks, they will be treated to a cutscene of either General Morden or Rootmars saving them.
• Large Ham: The announcers (except for the first one). "HEAVYYYY MACHINEGUN!" Allen as well: "AHAHAHAHAHA!! GO HOME TO MOMMY!"
• Later-Installment Weirdness:
  • Starting with 6, players are able to hold two weapons interchangeably, use the pistol while keeping their weapon ammo intact, and every character has their own characteristics.
  • The announcer from X to Advance has been replaced by a new one for 6, 3D and 7, likely due to the introduction of new weapons. A different announcer shows up in XX.
  • The last appearance of any character transformations was in the first mission of 5, where it was possible to turn fat.
• Leitmotif: General Morden and Allen O'Neil occasionally have "Assault" as their main theme whenever they appear or when they are involved, though the latter uses it as boss theme in 7.
• Lettered Sequel: The console ports and updated re-release follows this name pattern: Metal Slug X, being an Updated Re-release of Metal Slug 2, and Metal Slug XX is a PSP version of Metal Slug 7.
• Lighter and Softer: The original game had a relatively grounded military aesthetic and plenty of serious moments (such as backgrounds full of dead civilians and the credits roll that shows all the carnage you caused), with most of the goofier parts skewing towards Black Comedy. 2 and 3 introduced much more exaggerated enemy designs, a hammier announcer (introduced in X), Science Fantasy elements, and character transformations, although 3 slowly subverts this in its final level.
• Lightning/Fire Juxtaposition: The two Mutually Exclusive Power-Ups that are unique to the Elephant Slug are a hot pepper that gives it the ability to shoot fireballs, or a car battery that grants it the ability to shoot a lightning beam.
• Lightning Reveal: Used to show the Avatar of Evil's approach and departure in Metal Slug 5 as well with its scythe attack.
• The Load: The Chinese soldiers in the Beijing mission from Metal Slug 6 do nothing but chat (and spit on the floor), run around aimlessly, and on one occasion, holding a chicken with a meat cleaver on hand, in the middle of an Invader attack on their capital! Their only purpose is to act as hosts for Flying Parasites, an Invader bioweapon that can insta-kill even the likes of Ralf. This goes over to Militaries Are Useless, as the one's that do fight (through their MV-280C's) actively attempt to gun down the heroes combating the Invaders.
• Load-Bearing Boss: After the Doctor is defeated in Metal Slug 4, it causes his base to start exploding, leading to a sequence where you outrun the destruction.
• Locomotive Level: Metal Slug 2/X Mission 3 takes place on a conwoy of trains.
• Long Song, Short Scene: "Windy Day" in 5 is one of the best songs in the game. It's also only used in one location, that you can breeze through in less than a minute.
• Lovable Coward: The SV-Camel refuses to follow the protagonists into an ancient tomb in 2/X and into an army of man-eating plants in 3, but, unlike vehicles, it doesn't take damage and can't be destroyed (at the cost of not providing any cover for the player).
• Luckily, My Shield Will Protect Me: Some Mooks get a riot shield. They will hide behind it, slipping out every so often to take a potshot. When you shoot the thing out of their hands, they waste their Mercy Invincibility by panicking.
• Made of Iron:
  • In a series where most humans (including yours) die from a single shot, Allen and Morden both absorb several hundred rounds of machine-gun fire and/or dozens of direct hits from missiles and grenades every time they appear. Allen seemingly dies afterward only to show up alive in the next game, but Morden is just knocked into submission by it. Morden also has been known to survive a gigantic metal plate crushing him and being strapped to a spaceship as it launches into space.
  • Ralf is so badass he can take two hits instead of one. Including from a tank shell.
  • The Natives and Ptolemaic Cultists in 5 and the Hunters in 6 can take more than one hit, unlike most human mooks.
• Make Way for the New Villains: In Metal Slug 6 the villains appear to be both the Rebel Army and the Mars People again, up until the cutscene after the second level introduces an even greater threat in the form of the Invaders. For the rest of the game, you actually team up with the Rebel Army and the Mars People to take down the Invaders.
• Man-Eating Plant: The carnivorous plants found in 3 and 7 which can eat your character in one gulp. Even their seeds are deadly- touching them will cause them to kill your character in a writhing mass of vines. Bonus points for actually being called Man Eaters.
• Man on Fire: Using the Flame Shot on rebel mooks either turns them into a human-shaped Roman candle or set their upper bodies on fire leaving them running all over the place.
• The Many Deaths of You: Besides getting shot or stabbed, there are countless sprite animations for death, ranging from (while in fat mode) bursting like a balloon to getting sucked up by flying tentacle aliens to the various deaths when turned into zombies or mummies! Lots of these can result in some pretty severe feelings of terror.
• Marathon Level: Many final stages are quite lengthy, but 3's final stage deserves a special mention. It is literally about half the game's length, taking as long as half an hour to finish.
• Mascot Mook: The hapless Rebel Grunts. Many fans were saddened by their absence in the fifth game, and they even got to be playable in an unlockable minigame in the PS2 and Xbox ports of 3.
• Mecha-Mooks: The Martian Mechas (Ring Laser, Hopper, and Walker), Amadeus Robots, Ptolemaic Units, and the Rebel Walker.
• Mechanically Unusual Fighter: Out of all the slugs, The LV-Armor ammunition is limited and it can change its weapons depending on the ammo crates you pick up.
• Mechanical Monster: Many people wouldn't know what it was when they first encountered it in Metal Slug 2/X, given that only its "head" is visible, but the Aeshi Nero is a gigantic cobra-like excavator that's trying to "swallow" the pillar you're on!
• Mêlée à Trois: You get attacked by both yetis and zombies throughout the second stage of 3, but they're not on the same side. As you exit the Yeti's cave you can see some Yetis gutted to death by the zombies.
• Mercy Invincibility:
  • Jumping out of any Slug will give you a split second of this, and on top of that will leave the slug undamaged. This is often exploited to great effect in most no-death runs by jumping out of slugs to avoid projectiles that would otherwise hit the player.
  • The riot shield soldiers get this once their shields blown away...not that it does them any good, since the effect wears off immediately after they finish panicking.
  • The Iron Nokana has five in-game seconds of pseudo-invulnerability when it opens up its second phase. The player can keep damaging the tank until its HP reaches one, but the Iron Nokana will not accept defeat until it's shot after the invulnerability time passes.
• Mighty Glacier:
  • Most of the Slugs all take two to five hits to the player's one. However, their overall slower speed and lower jump height also make dodging harder.
  • While the Elephant Slug does not technically offer any protection, it is so tall that almost no zombies that are on the same floor as the player can hit them. Meanwhile, it can't jump and is as slow as molasses.
• Military Mashup Machine: Almost every boss you encounter - especially in the later games - is a great hulking mishmash of military vehicles. The classic Land Battleship (by which we mean, "A battleship with giant treads bolted on") Big Shiee makes an appearance in Metal Slug 2 (and X), and the very first boss in Metal Slug 3 is a giant hermit crab with a tank for its shell.
• Mickey Mousing: "Into the Void", the track that plays during the auto-scrolling part of 3's final mission, starts off triumphantly for the sky section, then gets more tense as you start encountering more and more resistance in the ground part (ramping up to the fight with Allen).
• Mind Control:
  • In Metal Slug 3, the character that you are controlling is abducted and then turned into clones, and then clone zombies.
  • In Metal Slug 6, one of the playable characters (which it is depends on the current Player Character(s) being used^note If P1 is Marco or Ralf, it's Fio (unless she is P2, in which case it's Tarma). If P2 is Tarma or Clark, it's Eri (unless she is P2, in which case it's Marco). If P1 is Fio, it's Marco (unless he is P2, in which case it's Tarma). If P2 is Eri, it's Tarma (unless he is P2, in which case it's Marco).) becomes controlled by the flying parasites.
• Mini-Mecha:
  • The Slugnoid introduced in the second game is a humanoid Slug with two Vulcan guns as well as a cannon on its...crotch.
  • The third game also has the Rebel Army's LV-Armor that you can use, being an armored version of the Slugnoid with functional arms. You can also equip it with the pick-up guns such as Heavy Machine Gun or Flame Shot.
  • The fifth game introduces Slug Gunner, a modified Metal Slug with legs, Pile Bunker arm and Gatling Good arm that can also deploy its treads to move faster. And an incomplete "prototype" version of it appears in the sixth game, with more standard vulcan guns.
  • The seventh game has a modified LV-Armor that has its own cannon and Vulcan gun.
• Mirror Boss:
  • Allen O'Neil, being a sole person with a gun and grenades, just like you. Except he can take an unrealistic amount of punishment before keeling over.
  • You also fight one of your fellow playable characters in Metal Slug 6, controlled by an alien. He/she has access to several of your special weapons, like grenades, knife/hatchet, the Heavy Machine Gun, Flame Shot, and Rocket Launcher.
• "Mission: Impossible" Cable Drop: The final level of Metal Slug 4 has the player descending down a tall chute and firing away at enemies left and right for the first part of the mission.
• Mole Monster: The first level of 7/XX has tiny mole-like robots that periodically lunge out from underground and charge at the player. If they miss, they disappear back underground and try lunging out again and again until they either self-destruct after colliding with and killing the player, or get shot in mid-air.
• Molotov Cocktail: Certain versions of the Slugnoid have an incendiary bomb as their bomb ammo, setting the floor underneath on fire.
• Mood Whiplash: Your commando can be mowing down infantrymen with a flamethrower one moment, and visibly complaining about the heat or cold the next, if he doesn't get his head bitten off by a giant locust first.
• Mook Horror Show: Human enemies panic when you respawn in front of them. Except for bosses, but everyone from the lowest infantry to blue-suited doom troops lose their shit.
• Mooks: With various animations and behavior, too.
• More Dakka: The Metal Slug franchise is heavily based off of awesome firepower, with heavy machine guns, BIG heavy machine guns, dual machine guns, and other powerful weapons. This is then taken even further by the fact that players can become fat, increasing the power of their weapons (think of a heavy machine gun that is BIG and while fat). The vehicles with a huge vulcan machine gun (or 2) are also based off of this.
  • Taken even further in Metal Slug 6 and 7, where playing as Fio immediately gives the player the (Big) Heavy Machine Gun. She also gets 50% more ammunition upon picking up other weapons.
  • In Metal Slug 2, there is much more dakka than the game engine can handle, resulting in significant slowdown. One thing about Metal Slug X being an Updated Re-release is that the engine doesn't drop frames quite so much.
• Mukokuseki: Were it not for her name, you'd never guess that Eri was from Hiroshima. In addition to having blonde hair (which can at least be handwaved as a holdover from her past as a sukeban), she is often drawn with a sharp nose: a trait commonly used to denote a character as being European in anime and manga.
• Multiple Endings:
  • In Metal Slug 4's final area, if a player gets caught in the explosion after the final boss, then the ending will show both players hospitalized. Otherwise, they'll show up with the rest eating a large feast on the streets.
  • Whoever saves the player in Metal Slug 6 depends on the route taken in Mission 4.
• Mummy: The second level in Metal Slug 2/X is an Egyptian tomb, which has mummies as enemies, which can turn you into one as well with their breath. They return in 3 and 4.
• Nerf:
  • In Metal Slug 6, either due to the weapon-stock mechanic or Fio being able to gain more weapon ammo, weapons have their ammunition reduced. For example, a Rocket Launcher would originally give out thirty rockets in earlier games, while in 6, Fio receives fifteen, the rest ten, and Ralf five. Metal Slug 7/XX reverts to its original amounts, so by the previous example, Fio now receives forty-five, the rest thirty, and Ralf fifteen.
  • While they still die after one shot, Rebel soldiers in X and on don't actually fall over after a single shot and can soak up bullets for a few seconds before keeling over (unless they get knocked over), indirectly nerfing the pistol and machine gun and making weapons that penetrate (such as the laser gun) more valuable.
• Never Gets Fat: Subverted in Metal Slug 2 and onwards; eating enough dropped food items will make the player character(s) fat. This slows them down a bit, but also strengthens their firepower.
• Night of the Living Mooks:
  • 2 has an Egyptian tomb populated by mummies, X adding mummy dogs.
  • 3 and 4 have zombie-themed levels as well as the mummies.
• Ninja Pirate Zombie Robot:
  • Green alien zombie clones that puke streams of blood in Metal Slug 3.
  • The zombies in the second level are caused by an alien meteorite possessed by creepy brain-dead cyclops aliens (Monoeye) that attack by dropping monoliths on you.
• Nintendo Hard:
  • Not surprising, since arcade games need to be able to get your quarters. There is a rule among fans: "When fighting a boss, use all your grenades immediately. You'll die and get a new set in a few seconds." Metal Slug 1 was hard, yet still the easiest of the games. 3 and 4 are the most difficult, and one could say the purchase of any one of the games for a home console will pay for itself in saved quarters very quickly.
  • Mike Uyama, speedrunning legend, explicitly states here it's harder than Contra III: The Alien Wars. And he beat that game in 15 minutes.
    From Uyama himself: "Metal Slug 3 is longer, has more randomness, bosses don't die as quickly, and the hardest difficulty is considered impossible (or nearly impossible) to beat on one life. Whereas in Contra III, the game moves quickly, but there isn't much randomness. If that doesn't convince you, Contra III took me 10 days (this includes both practice and recording), Metal Slug 3 took me over a year."
  • The developers know that a very tiny fraction of clears will be proper clears done on one credit, because the ending result screen shows how many continues you used up. It's not uncommon to see, for instance, a continue count of 50 or more (in other words, over 150 lives lost) on Metal Slug 3, especially given that it's longer than the other ones.
  • Exaggerated in the original Xbox port of 3 (not to be confused with the Xbox 360 port). Using a continue starts you from the beginning of the level. If you've played the game, you'll know that expecting a player to complete the final mission on a single continue is nothing short of insane. This is particularly grating considering the otherwise identical PS2 version (not released in the US) has unlimited continues. It is possible to effectively double your lives on 1-player mode by having two controllers plugged in, and pressing Start on the second immediately after you lose your last life on the first, but that's still a maximum of ten lives.
  • If you think the side-scrolling shooter games aren't hard enough, 3D is very difficult, good for Third-Person Shooter standards but still brutal for a Metal Slug game. Even with Anti-Frustration Features like stacking weapon ammo, ability to lock-on targets and infinite continues, the stage designs are very challenging. To top that, you have a final mission which is a Boss Bonanza of two SNK Boss-only levels and nothing else.
• No Celebrities Were Harmed:
  • The Big Bad Morden bears an uncanny resemblance to Saddam Hussein. According to the game's Back Story, he's actually from the province of New Brunswick in Canada.
  • And his right hand man Allen O'Neil looks an awful lot like "Stone Cold" Steve Austin cosplaying as Rambo.
• No Swastikas:
  • Mercilessly parodied via the enemy army, who aren't actually Nazis — even in the Japanese version — but wear Nazi uniforms, and have insignia strongly resembling poorly-censored Nazi symbols: Swastikas become plain black X's and eagles become Phoenixes. It could be a Shout-Out to Charlie Chaplin's The Great Dictator, since the former symbol appears in the movie.
  • See also the insignia on the enemy tanks -that, by the way, resemble World War II German ones-. It looks like a Balkenkreuz rotated 45 degrees.
• Non-Indicative Name: The Regular Army is woefully undermanned, with their operatives and captured soldiers being lightly armored in person, though not really underequipped, while The Rebel Army is suspiciously well-organized for a rebellion, including nigh-limitless regiments of troops, armored division, and experimental weaponry.
• Not Completely Useless: The Drop Shot is widely regarded by players as the most useless weapon in the entire game, due to its projectiles bouncing around slowly and being difficult to hit a player's intended targets, coupled with its explosion being extremely weak. However, it is useful during the battle against 7's Fall Climber, a boss fight in which you are literally standing on said boss. Conveniently enough, one of the nearby prisoners during this boss fight will give you a Drop Shot.
• The Nudifier: The "slimy protagonist death" animations. Males get Stripped to the Bone. The girls, on the other hand, get their clothes dissolved as they keel over, with a brief moment of cleavage or Panty Shot before they just disappear into a green mush.
• Octopoid Aliens: The Mars People resemble octopi that can stand on their tentacles and wield rayguns. They also curl up into something resembling a jellyfish to glide short distances.
• Oddball in the Series: Metal Slug 5. General Morden and his army are completely absent and is replaced by a whole new military unit called the Ptolemaic Army, whose ranks consist of cultists worshiping a demon god. The mascot vehicle of the series is not the Metal Slug anymore, but a whole new vehicle called the Slug Gunner who actually shows up on the intro screen. And ever since the first game, Metal Slug 5 has no supernatural elements in it either ( save for the demon that inexplicably shows up as the Final Boss) and the game itself lacks plenty of the dark humor as seen in its predecessors. Apparently, Metal Slug 5 was was actually supposed to be an original game on its own before being changed into a part of the Metal Slug series.
• On-Ride/On-Foot Combat: You're on foot most of the time, but there are times where you get a Slug you can ride in/on, and they come in all sorts (tank, plane, Mini-Mecha, camel, etc.) and you can (usually) ride them all the way to the end of the stage (if you can make it last that long). That said, there are also cases where you're forced to leave your ride behind, so the game has cases of this trope both played straight and averted.
• One Bullet at a Time: Well, more like Two Grenades At A Time. Getting in close and lobbing grenades like a maniac isn't just the key to speedruns — sometimes it's the only remotely easy way to clear an area.
• One-Hit Kill: Certain attacks can kill Ralf (such as getting eaten by Man Eaters) and Slugs (e.g. being crushed by Dragon Nosuke or Metal Rear) in one hit.
• One-Hit-Point Wonder: It's an arcade Run-and-Gun game, so no surprises here. If you're in a Slug, it will take 3 (or rarely 4) hits for you. There are, however, some aversions:
  • Getting hit by mummifying gas/potions or scientist darts won't kill a character in one hit, but they'll be turned into a mummy or monkey respectively. If they're hit again by the stuff that transformed them, or other attacks, they die.
  • Getting hit by zombie puke won't kill a character in one hit, but they'll be turned into a zombie. If they're hit again by zombie vomit or certain other attacks, they die, but as a zombie, your character is immune to most conventional attacks like bullets/grenades.
  • Ralf in Metal Slug 6 and 7, who can take two hits. He's just that tough! Considering how close Ralf needs to get to tanks in order to use his anti-tank Vulcan Punch, it's quite helpful. It is also most likely a Shout-Out to his The King of Fighters '99 victory quote "I can survive anything - even nukes!".
  • From 6 onward, putting Tarma in a Vehicle doubles its defense, letting you take twice as many hits.
  • Interestingly enough, Metal Slug Advance gave you a life bar (refillable through eating food). Played straight, however, upon activation of the "Paper Thin" card. Completing a level with it gave you another card for 100% Completion. The same happened in Neo Geo Pocket Color's Metal Slug 1st Mission and 2nd Mission, but it was a bit harder to activate the "Paper Thin" mode, which also enforced you to use the Taser Glove and Zantetsuken.
  • In Metal Slug 3, getting run over by an Ohumein-Conga or a Division 6's Samurai Tank won't kill you, but rather knock your character down, causing them to get up afterward (though you lose special weapons in the process). Getting hit by Robot Allen's melee attack in 4 has the same effect.
  • 3D, being a Third-Person Shooter, has an interesting variation of this: the life bar system subtly avoids this trope, allowing you to take more than one hit in most situations. Emptying all the life bar, or in certain One-Hit Kill situations (such as falling Into Bottomless Pits), however, nets you an instant game over with the option to continue on last checkpoints or going back to the menu.
• One-Man Army:
  • Sometimes the Mooks actually scream and run for their lives if you approach them. They know. This is usually after they've killed you, only for you to accept the Continue screen and come back again. For some fun, find two soldiers chatting with each other. Kill one and watch his friend freak out and run.
  • Subverted in 3D story-wise; instead of one-man army as gameplay implies, the protagonists work in a four-man Sentai-like operations in some cutscenes.
• Optional Boss: The Black Hound in 5 is an optional boss found in a secret area of the first level.
• Painfully Slow Projectile: The NOP-03 Sarubia (tall gray tanks) specializes in shooting slow-rolling bombs to force the players to dodge and jump, making them easy targets for its allies.
• Painting the Medium: The first mission of Metal Slug 2/X features a different type of lettered font when collecting grenades; nothing of a sort happens in other games.
• People Jars: Mission 5 in Metal Slug 6 sees you rescuing Mars People from these sorts of jars.
• Phallic Weapon: The Slugnoid cannon points straight down between the legs.
• Pile Bunker: The Slug Gunner has a pile bunker powered by a revolving chamber.
• Piranha Problem: The Flying Killers in 3 and 6. Jump in stage 1's water in 3 and they rip you to shreds. They can also jump out of the water and fly at you.
• Pocket Rocket Launcher: Similarly to Contra, every weapon besides the pistol and (for the games that have it) the Zantetsu Sword, uses the machine gun sprite, including the Rocket Launcher (high damage rockets with slow travel and a slight homing capability), Enemy Chaser (high travel speed, greater homing capability missiles), Super Grenade (dumbfire rocket-propelled grenades with similar power to a tank shell), and Iron Lizard (novelty weapon; rocket-propelled toy cars carrying a bomb).
• Power-Up Food: Roast turkeys, live fish, lettuce, eggs, dim sum, carrots, mushrooms, and other foods can be collected for points. Collecting too many will make you fat, which means that you move slightly more slowly but your weapons become more powerful.
• Power Up Letdown: Plenty.
  • There's a tendency by the developers in giving the player inferior weapons that replace much better ones, particularly in Bullet Hell sections that require weapon versatility, power or both. One of the most common situations is the placement of Drop Shot/Iron Lizard crates in sections that require the player to fire in platforms above them (such as the Yeti section in Mission 2 of Metal Slug 3), or a Shotgun crate when the enemies are on positions where a replaced Heavy Machine Gun would have been able to actually hit them.
  • The first game's version of Flame Shot is so pathetically weak it is only good against soldiers. To put in perspective, it takes 13 shots to destroy an R-Shobu, almost half of the weapon ammo.
  • The Fat version of Rocket Launcher. Not only do the missiles fire slowly and erratically attempting to chase enemies, the player is also limited to shooting them only until the previous batch leaves the screen or hits an enemy, which can easily mean dying in segments packed with targets.
  • Drop Shot's landmines bounce with limited reach, are weak against vehicles, and are also limited by the geography around them. It's only useful when used against soldiers hiding behind obstacles, but even then, you have to properly time and distance your shots lest you want to waste ammo.
  • Iron Lizard's drones are extremely useful against infantry and can travel long distances very fast, but explode in contact with any enemy, are weak against armored vehicles, and can only deal with grounded units - unless you take your chances shooting them directly under a platform.
  • The Stone "upgrade" for your grenades. They don't explode like normal grenades and are terrible against armored enemies and vehicles, just to slightly increase your throwing range - in a game where you have an infinite ranged weapon.
  • Any of the animals mounts if you're playing Ralf in the later games. While the infinite-use machine gun is nice (unless you're playing on easy mode and it's the default weapon instead of the pistol), you can't also use Ralf's powerful melee attack and he dies in one hit instead of taking two like when he's on foot.
• Precision F-Strike: It sounds like Tarma is letting one out upon dying, which is supported by the fact that the bowdlerised PS1 release of X replaces his death scream with Marco's. This can quickly turn into Cluster F-Bomb given the game's Nintendo Hard nature, which makes his aversion to swears in story-driven installments such as 3D and the tower defense games all the more surprising.
• Prequel: Metal Slug: 1st Mission and 2nd Mission both take place before Metal Slug 1.
• Purposely Overpowered: The "Super Devil Mode" in the Combat School missions gives your character green skin and replaces their regular pistol shots with Metal Slug cannon shells (in 1 and 2) or Super Grenades (in X). It's a Bragging Rights Reward, however, since you only get it once you have achieved the highest scores in Combat School already.
• Qurac: First level of Metal Slug 2 (and X). One would assume that's why the next level has mummies, too.
• Rank Scales with Asskicking: Morden himself can absorb hundreds, if not thousands of rounds, and is only defeated because the vehicles he rides in aren't quite as tough. He is fully exposed during the penultimate boss fight of 7, and the protagonists don't even bother shooting at him.
• Rated M for Manly: The series has Stuff Blowing Up, Large Ham, Announcer Chatter, Awesome Music, More Dakka, Contra-level of Nintendo Hard, Ralf, Clark, and Leona from The King of Fighters being included in future entries. This series will surely make your Neo Geo grow some balls and chest hair as well as a beard and will make you a man.
• Real Is Brown: Being set in a deserted island full of garbage, Metal Slug 7 has its environments be full of brown or one color in some areas. The sixth mission and the final boss arena are the only two exceptions.
• Recurring Boss:
  • Crablops in 7 appears as the second boss but doesn't explode to bits when beaten. It then reappears as the third boss...but it now detaches its top and bottom halves to attack you separately.
  • The Iron Nokana gets piloted by Rebels, Arabians, and Amadeus at three separate times throughout the series, in 1, X, and 4, and Shoe gets fought three times as well, twice in 1 and once in 2.
• Recycled In Space: Contra and Super Sentai together AS AN SNK GAME!
• Recycled Title: The 3D Metal Slug game for the PS2 is simply titled Metal Slug.
• Red Ones Go Faster:
  • The orange Type-R Slug sacrifices power for maneuverability.
  • The deep red Type R Slugnoid is much faster than the others, but it's still not as fast as even the SV-001 Experimental.
• Redshirt Army: Whenever you team up with the Rebels to fight either the Martians or the Invaders, they become this.
• Rewarding Vandalism: If you destroy any objects in the background, chances are it'll drop a useful item or food, and enough food will turn you fat, which will upgrade your weapons. On the other hand, your walking speed is slowed down in the process.
• Ring Menu: On some of the console versions.
• Robotic Reveal: Fighting General Morden and Allen O'Neil reveal them to be robot duplicates in Metal Slug 4.
• Rule of Cool: Going over its silly nature, this is the only reason as to why some of the Rebel Army infantrymen are issued with man portable mini-guns with an ammo pack for an automatic weapon (normally an Awesome, but Impractical weapon in real life). When a Ptolemaic guerilla pulls out a practical submachine gun to mow you down, you know that these guys mean business.
• Sand Worm: A giant flying worm is the fourth boss in 6. However, you face it in a bay.
• Samus Is a Girl: As revealed in Metal Slug: 2nd Mission, some of the bearded prisoners that you rescue are female, confirming that their general appearance is a disguise. The second ending for 1's "Another Story" even have a POW shed a disguise to reveal that this particular POW is a female in a bikini.
• Schizo Tech: The Rebels' hardware is a mixture of World War II, including one land version of the Japanese Yamato battleship and Sherman-like tanks, and modern vehicles as an Apache-like helicopter. Meanwhile, yours include a Harrier jet and one background event in 2 is a Boeing 747 taking off.
• See You in Hell: Allen O'Neil's death cry, and one of his catchphrases.
  Allen: I'll see you...in hell...
• Self-Deprecation: Tactics features a billboard advertising the Neo-Geo AES for ¥100,000, parodying how the console was unaffordable for the majority.
• Sequential Boss: A few bosses in the series do have a second or even third phases.
• Serial Escalation:
  • 2 introduced supernatural and sci-fi elements, but they weren't that many and it was rather conservative with them ^note The mummies are confined to the second mission, the exploding mutants only appear in a single section of the fifth, and the aliens don't show up until the last portion of the final mission, though they have an expanded role in X. 3, on the other hand, ramped up these elements considerably: the very first mission pits you against mutated crab monsters, giant insects and flying piranhas; the following mission is a Zombie Apocalypse (with the chance of fighting yetis depending on the path you take), the fourth mission features the mummies from 2, Man Eating Plants and an underground tunnel filled with giant insects, snails and worms; and lastly, 2/3 of the (extremely long) last mission is spent fighting against the Mars People.
  • Zigzagged as the series progressed: 4 focuses much more on human enemies, featuring only yetis on the third mission and mummies and zombies on the fourth (on different branched paths each); 5 is the first game since 1 not to feature any kind of fantastic or sci-fi element with the exception of the Final Boss. 6 brings back the Mars People, and introduces a new kind of aliens, the Invaders, who become the main antagonists in the second half of the game; 7/XX focuses on human enemies entirely once again, with the twist that they come from the future and thus use futuristic technology.
• Series Fauxnale: SNK was nearing bankruptcy during the development of 3 and decided to have one last hurrah (however, tentative but ultimately unused ideas for a fourth game did exist at the time). As a result, the craziness of the previous games is turned up to eleven and the final mission is equal parts Nostalgia Level and Marathon Level, culminating with a Free-Fall Fight with the leader of the aliens and ending with the main character throwing their gun as a symbolic gesture that the war is over. Nevertheless, the fourth game came out just two years later.
• "Shaggy Dog" Story: Elephant Slug starts to help you after you free it from the ice it's trapped in. In the end, the player either abandons it among the zombies or leaves it trapped in another pool of ice.
• Shock and Awe: Several enemies use electrical attacks.
  • The Hozmi submarine from 2/X and future rebels from 7 are prominent examples-the latter going so far as to have tesla coil armed specialist infantry and electrified gauntlets replacing knives as standard-issue close combat weapons...
  • You also have the Thunder Shot from 7 and the Thunder Cloud from 3.
  • The Elephant Slug can shoot electricity from its trunk if it eats a car battery.
• Short-Range Shotgun: The Shotgun's explosive bursts can't even reach the midpoint of the screen ^note most of your munitions in this series travel the length of the screen, but can scrap enemy tanks in a few shots. The "Big" Shotgun, first seen in X, does hit half the screen.
• Shout-Out: Now has its own page.
• Shows Damage: Taking damage causes the Slugnoid to lose a gun.
• Simple Rescue Mechanic: Shooting a hostage releases them from ropes, and reaching them has them reward you with a pickup before they run off screen.
• Sink The Life Boats: If you destroy one of Morden's boats, the soldiers will get out and the ship will break apart... but when the smoke clears you'll see the boat, now tilted upward dangerously and obviously crippled, with a lone weaponless soldier desperately trying to bail it out. You have to destroy every enemy to move on during most screens, and while the boat's still floating, it counts. Do note, enemies will file out if you take too long.
• Sliding Scale of Silliness vs. Seriousness: Despite the series' war setting, everything in the game isn't taken too seriously. The first game and the Neo Geo Pocket games (the earliest in the games' timeline) are the most serious of the bunch, but then you look at how silly the enemies react, the large, fantastical tanks they own, and your player character's arsenal. SNK's take on Super Sentai, of course.
• Smashing Survival: If you get turned into a snowman thanks to yeti ice breath, smashing the buttons and rotating the joystick will help you get out before the yeti hits you with a bone club.
• Sniping the Cockpit:
  • This is the LV-Armor defeat animation as the rebel soldier within gets killed. If you lack a Slug, it'll become rideable, otherwise it explodes.
  • Subverted by the Jet Hammer-Yang speedboat enemies. Their pilots are very exposed to harm and in fact die in one hit, but killing the pilot does not stop the boat from firing its homing missiles. Only by destroying the boat (which is far more durable than the pilot) will put a stop to them.
• Spin to Deflect Stuff: The Invaders in Metal Slug 6 use this tactic quite often — if you shoot them with a pistol or Heavy Machine Gun while they are spinning, the bullets will bounce off of them. Despite this, they still take damage. They also roll on the floor and spin-jump around like a certain blue hedgehog.
  • The PF and SPARROWS commando clones in 3's final level (spaceship section) deflect HMG and Vulcan bullets while jumping ala Contra.
• Spiritual Successor:
  • Metal Slug shares a lot of graphical and gameplay similarities with the earlier shooters In the Hunt and Gunforce 2, both of which were made by the same team. It also shares a lot of visual design and trope usage with Undercover Cops, a Beat 'em Up also developed by the said team.
• Stock Scream: If the mooks get set on fire or blown up, they'll often let rip one of these (a couple of which are reused from the aforementioned Gunforce 2). Also, if you die, they laugh and shrug as if to say "what was the big deal?"...only to freak out when you come back thanks to the magic of extra lives.
• Stripperific: The female SPARROWS uniform includes a midriff-bearing tank top and a pair of shorts with hips vents◊ Subverted in the fact that they offer as much protection as any other uniform (as in none).
• Strong Flesh, Weak Steel: The special ability of Ralf is to punch right through tank armor.
• Stuff Blowing Up: Tanks, cars, alien technology, anything that can be shot at will explode.
• Sunken Face: Not in the games itself, but in one of the behind-the-scenes concept art of Metal Slug X shows a rebel soldier's entire face sunken in after being hit by a bullet, rather than the more realistic Boom, Headshot!. The picture can be seen in the game's gallery after beating the final level.
• Super Drowning Skills: Unless you have the appropriate equipment, your character will die upon falling on water.
  • Justified in Metal Slug 3's Mission 1. The water is infested with man-eating fish that will strip a character down to their skeleton should they fall in (though oddly enough neither the POW or a Rebel suffer the same fate if they do the same). Incomparably frustrating if this happens while missing the jump to the Marine Slug (and associated level path).
  • Also justified in Metal Slug 2/X's final mission. The water is ICY COLD and a drop in it will make your character frozen in an ice block (again no Rebels are treated in the same manner if they fall too).
  • And justified in Metal Slug 6's mission 1's river, the current was rapid. And mission 2 had the same flying piranhas!
• Super Prototype:
  • An advantage the SV-000 has over the SV-001 is the ability to turn around fairly easily. Unfortunately, the exit hatch is easily warped, making the thing into a deathtrap if it gets hit at all.
  • The Slug Sub is actually the prototype of the Slug Mariner, despite its more diverse moveset.
• Suicide Attack: Both the Mutated Soldiers in 2/X and their Suspiciously Similar Substitute Hopper Mecha enemies in 3 turn red/yellow before exploding on the player as their only attack.
• Surprisingly Realistic Outcome: In 3's Mission 5 during the ground area, you will encounter a row of three Landseeks driving in a straight line. Destroying the lead Landseek will cause a domino effect where the other two following Landseeks crash into one another, destroying themselves in the process.
• Survivor Guilt: At the ending of the first game, in the second mission, you find what has usually presumed the daughter of a dead enemy soldier. Jump at 2:44. She only appears if you finish in one player mode, where the credits scroll over the destruction you left behind (graves, devastated buildings, wrecked tanks, etc).
• Suspicious Videogame Generosity: Right at the end of Metal Slug 6. No enemies, no music, and a Metal Slug for you to ride.
• Tactical Suicide Boss: Rootmars, the final boss of Metal Slug 3, holds the player's metal slug in his hand during all the battle for no reason, allowing the player to exploit the Mercy Invincibility obtained from entering or jumping out of the vehicle to avoid his almost impossible to dodge attacks.
• Taking You with Me:
  • When killed, the red Samurai Infantry in Metal Slug 3 hold a stick of dynamite and blow up with it, taking out the player character if they're too near. Metal Slug Advance makes all Japonese soldiers do this.
  • When the Mars Mecha enemies are destroyed, their body falls off their long legs and crashes into the ground. This can crush the player characters and rebel soldiers if they're standing under it when it lands on them.
• Tank Goodness: An incredibly cute example, with a strong resemblance to the mini-tank from Dominion Tank Police.
• Tank-Tread Mecha: The fifth game introduces the Slug Gunner; a new variant of the titular Metal Slugs that is a Mini-Mecha instead of a normal tank, complete with arms (one with Gatling Good and another with Pile Bunker). It can retract its legs to deploy the treads, making it faster, but limiting its shots' direction (only forward).
• Technically-Living Zombie: The player characters when zombified are technically still alive but infected with a disease, considering that picking up a simple medkit will instantly turn them back to humans. This doesn’t happen with enemy zombies, who are legitimately undead according to Metal Slug Attack.
• Temporary Bulk Change: Starting in Metal Slug 2, eating a certain amount of food in a short amount of time will turn your character obese, slowing down movement speed and providing a bigger target for enemies but also increasing the damage of weapons. It also goes the other way, as there is a "Diet" item that lets you slim down instantly (it can happen automatically as well, but it takes longer).
• This Is a Drill:
  • In one path of Metal Slug 3, you get a Drill Slug, which can drill right through those nasty big creepy crawlies. Ichor spews EVERYWHERE.
  • The first boss of 7/XX is a giant worm-shaped drill robot, which continuously burrows in and out of the floor and ceiling. Its body is divided into segments that spawn enemies and drop grenades; however, concentrated fire can destroy each segment, and damage anywhere on the boss (even on destroyed segments) is applied to its overall health.
• This Looks Like a Job for Aquaman: Some of the vehicles seem to have been custom made for the boss fight or sequence they're available for:
  • The Slugnoid can only really shine in situations that require more vertical movement than horizontal, typically during a vertically-scrolling fight. Also, the fact that its missiles travel downward means it's only really useful when an enemy is directly below you. It appears to be designed with fighting the Aeshi Nero and Hozmi in 2/X.
  • The Slug Flyer usually only available when enemy planes are about, an exception being 2/X where it can be used against the Dragon Nosuke.
• Too Awesome to Use: New players often get this mindset with the grenades or specific weapons (like Enemy Chaser or Rocket Launcher), especially in 7 and XX, where you can "unequip" weapons for later use. Most are quickly cured of this mindset as soon as they die and lose said equipment without getting to use it.
• Trampled Underfoot: The Elephant Slug can kill humanoid enemies merely by walking over them.
• Transforming Mecha: The SVW-001 can switch between a Tank and a Mini-Mecha form.
• Trick Bomb: Aside from the standard stick grenade, there's also the Fire Bomb and Stone. The regular grenade explodes in a vertical burst that does good damage to machines and kill several on-foot enemies in one go. Fire Bomb explodes in a spread of flames, making it good against swarms of on-foot enemies but not on machines. Stone can only hit one target at a time, so it's not good on on-foot enemies, but has increased range.
• Trick Boss:
  • The Final Boss of Metal Slug 6 is a yellowish alien core thingy. It doesn't even move, and is aided by only a few mooks that come at moderate intervals. Rebel soldiers also come in to deal some damage (and die to the mooks as well). After defeating it, more Rebel soldiers come in and celebrate your victory over the enemy.. when the alien in the destroyed core fires out a destructive wave, killing all of them. Time for the REAL final boss battle.
  • Done again in Metal Slug 3D, though the first "battle" is against an actual challenging enemy.
• Trouser Space:
  • The POW takes this a step further by keeping powerups in their underwear.
  • The alternate route in Metal Slug 3 leading to the underground camp has Japonese soldiers who fling bombs from their boxers.
• Truth in Television: While the SV-Camels might look goofy and unrealistic, camel-mounted machine guns actually existed in real life, called zamburaks.
• Turns Red:
  • Allen O'Neil turns red gradually as you hurt him more. He might change his pattern a little bit, but the major point to him turning red is to assure you that, yes, you are in fact making progress.
  • Similarly, Sol Dae Rokker in Metal Slug 3 will gradually turn red as it takes more and more damage, along with gaining extra fire rate and deciding that two explosive ghost wolves at a time isn't enough anymore.
• Uncommon Time: No two versions of "Steel Beast" (the boss theme of the first Metal Slug) share a time signature (except 2 and 3).
• Undead Counterpart: The third and fourth games has both recurring rebel soldiers and zombie rebels in undead-themed levels, who assault the players with a pouncing tackle which functions like a Suicide Attack, killing themselves in the process. Oddly enough, the game shows innocent civilians and bystanders getting zombified onscreen, but not rebels - existing zombie enemies seem to ignore rebel soldiers while assaulting the players.
• Unexpected Gameplay Change: Occasionally, Metal Slug games will shift from a Run-and-Gun to a Shoot 'Em Up. Okay, so they're not all that different as genres (some people class the former under the latter, even), but the way you play changes a bit.
• Unexpected Shmup Level: The Slug Flyer tends to appear in several Shoot 'Em Up-like segments of the games, turning the game into a Shmup.
• Ungrateful Bastard:
  • Despite saving his ass (and organization!) in both Metal Slug 2/X and 3, Morden still tries to kill the protagonists in 6 and 7/XX. Although he is leader of the world-wide rebellion which the player opposes.
  • For what it's worth, though either Morden or Rootmars will save the player at the end of Metal Slug 6, depending on what route you took in stage 4.
• Unique Enemy:
  • There is only one yellow Rebel in Metal Slug 3.
  • There is also one Golden Hunter Walker in Metal Slug 6 only seen by crawling through a specific tunnel.
  • A single Golden Bat is generally found in one area in some of the games. Touching it when it's still alive will collect it for a massive amount of points.
• Unstable Equilibrium: By the end of a given stage, the POWs you rescue (especially if any of them are special POWs) and whatever Slug you can carry to the end of the stage will be worth hundreds of thousands of points, or even a million or two. It takes only a single life loss—even if it happens with the end boss down to three pistol bullets left—to lose all of those rewards, and if you were in an armored Slug, chances are it'll be blown the hell up before you finish the boss. All of this in a sadistically Nintendo Hard series.
• Unusually Uninteresting Sight: In the first stage of X, there is a pair of background NPCs who keep on chatting calmly even as you start gunning down mooks. They'll run away only if you shoot at them specifically.
• Unwilling Suspension: More often than not, you can find prisoners being strung from treetops, high platforms or ledges by their wrists overhead (except for soldier variants who is hanging by their ankles instead), hanging in midair until you shoot the ropes to release them. Prisoners dropping from higher levels would make a flapping motion with their arms as they fall before landing.
• Unwitting Instigator of Doom: The girl praying at the end credits of the first game is apparently praying for a UFO to come and resurrect her loved one. If the Mars People indeed did arrive thanks to her call, causing the events of 2, 3, and indirectly 6, then her prayer had caused far more trouble than her intention.
• Updated Re-release:
  • Metal Slug X was a major redesign of Metal Slug 2, to the point where it introduced more iconic elements to the series than 2 did. Besides the much-maligned slowdown from 2 being greatly reduced, X also introduced the Iron Lizard, Drop Shot, Super Grenade, and Enemy Chaser weapons. It also gave us the BIG versions of the Original weapons (Heavy Machine Gun, Rocket Launcher, Shotgun, Flame Shot, and even the Laser Gun), numerous new enemies, and increased difficulty.
  • XX is an updated version of Metal Slug 7 (originally on DS) released for the PSP and Xbox Live Arcade.
• Victory Pose: Each character will do a victory pose at the end of a mission, except for the first game where they simply stand in place. When playing in co-op, the better performing player gets the honor of doing their pose.
• Video Game Flamethrowers Suck: The Flame Shot plays this straight in the first game, where it did kill soldiers regardless of shielding, but did pitiful damage to vehicle enemies. This was fixed in 2/X where it kills troops with ease and now tears vehicles apart in as little as two to three shots.
• Video-Game Lives:
  • By default, three lives per continue. In the arcade versions, the only way to get more lives is to put in more quarters, although the console versions allow you to edit it to higher amounts, with Metal Slug Anthology's Free Play effectively rendering them Meaningless Lives.
• Vulnerable Civilians: Civilians are in danger whenever mummies and zombies are involved. Those hit by mummy breath or zombie vomit will be transformed into one of the undead. Some zombies will even actively go for infecting the civilians.
• Walking Shirtless Scene: Allen O'Neil always fights without a shirt, showing off on how absolutely ripped he is.
• Walking Tank:
  • The Slug Gunner from 5.
  • The Slugnoid walks on two short, stubby legs.
  • 3 has a Mook which is quite literally a hollowed-out tank◊ carried by two Japonese soldiers, with a third as the commander.
• Wave-Motion Gun: The Laser Gun from Metal Slug 2 onwards. Shown LITERALLY in-game if the player fires a Laser Gun or BIG Laser Gun while fat.
• Weaponized Animal:
  • The Camel Slug, Elephant Slug, Ostrich Slug, and Donkey Slug, animals with a rapid-fire gun attached to them.
  • On the Rebel Army's side, we have Huge Hermit, a huge hermit crab with a tank for its shell.
• Welcome to Corneria: Allen O'Neil's pre-programmed dialogue while he battles the players, which consists of "Come on boy! Go home to mommy!" in EVERY. SINGLE. GAME. While it makes sense in the first due to Marco and Tarma being the only playable characters, in the sequels if players are assuming the role of a female commando (Eri, Fio or Nadia) Allen will still continually taunt them with a "Come on boy!"
• Well-Intentioned Extremist: General Morden himself for the entire series except 5 - trying to take revenge for the Totally-Not-The-UN killing his son, and Oguma in Metal Slug 3D.
• What Measure Is a Mook?: The 1P ending of the first game has a paper plane fly past a long line of Rebel Army corpses, complete with someone mourning at a grave.
• Womb Level: The Invader Nest from Metal Slug 6 and Lieu from Metal Slug 3D
• Wolfpack Boss: The Union from 7, which is made of three enemies that attack separately. "Killing" one part makes it stop attacking, but it's still usable as a platform.
• The Worf Effect: The first game sets up Morden as an influential, well-armed, and nearly indestructible general. The second and third games allow the Mars People to humiliatingly defeat him to show how much more dangerous they are. The sixth game demonstrates the Venus People as an even greater threat by showing them obliterating Morden and the Mars People.
• You Can't Kill What's Already Dead: When your player characters are zombified, they become invulnerable to conventional damage including grenades, bullets, helicopter bombs, tank shells, or getting run over by the tank. Only a few things can kill a zombified player, unfortunately, one of them happens to be getting hit by zombie vomit again and another happens to be all of the level boss' attacks.
• Zeerust: Most of the "High-Tech" devices in the series are intentionally Zeerusty, from the aforementioned land battleship, to pulp robots, to 50s B-movie flying saucers. In particular, many vehicles (including aircraft) appear to be constructed of heavier metals riveted together.
• Zerg Rush: There are a few sequences like this in the series, but the best one might be the ridiculous Venusian onslaught in Mission 3 of Metal Slug 6. They just keep coming in from the right and coming in from the right...
• Zombie Apocalypse: The second level in Metal Slug 3 pits you against zombies, apparently caused by an alien-infested meteorite. They reappear in 4 with no context, though the virus has apparently been studied and weaponized in the interval between the two games. You can be turned into a zombie, which greatly reduces your walking speed and and confines you to using your pistol, but gives you an obscenely powerful blood vomit attack instead of grenades and makes you immune to normal mooks' attacks. Later in 3, evil duplicates of the player get turned into zombies… and unfortunately also have the blood vomit attack (which just kills you outright, instead of zombifying).
• Zombie Puke Attack: Zombies attack solely by this method (although the release method is different between types: for example, fat zombies will let the puke burst out of their ribcages, while zombie scientists will pull out their intestines and squeeze the bile out at you); when a player character is zombified, their grenade attack is turned into a bloody version of this.
• Zombify the Living: The zombies' vomit attacks will turn your player characters as well as the injured but still-alive civilians into zombies.

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''MISSION ALL OVER!''

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