Coach: "Wait for official instructions. (laughs, tossing away instruction sheet dismissively) 'Wait', my ass." Ellis: "Kill all sons-a-bitches. *racks shotgun* That's my 'ficial instructions."
The 2009 sequel to Left 4 Dead.The plot is roughly the same as the last game, a deadly virus epidemic has claimed the country. You play as one of four survivors trying to make their way though bloodthirsty hordes of mutant infected to reach safety. The difference this time out is the setting is located somewhere around the Louisiana area.The game sports a few new features such as three new special infected (The Charger, the Jockey, and the Spitter). Also introduced in the sequel is the new Scavenge mode, a eight-player mode similar to Versus where the point isn't to reach the safe room; it's to collect gas cans. Also introduced is Realism, where most auras are removed (including the ones around teammates), Witches instantly kill on any mode except Easy, there are no "rescue" closets (dead players only respawn at the start of a new level), and a few other things. The narrative to the game has also changed as each campaign now leads into the next one rather then stand alone (for the most part) like the first game did.The lead up to the game saw much controversy after it was announced at 2009's E3 and was set to be released in November that year. Unfortunately, Valve's claim at launch of the original game that they would update it following the model of Team Fortress 2 updates promptly backfired, as large numbers of people were outraged that they were expected to buy content they were under the impression they'd either get for free, or get as a mod rather than an entirely new game; this gave rise to the biggest outburst of "ruined!" cries ever: a 40,000+ people boycott. A couple months before the sequel was due, Valve flew both leaders of the boycott to Valve's headquarters to playtest the game, where they admitted that it was "well-made". After Valve's release of a new campaign for the original, "Crash Course", and the leaders admitting that the boycott had since become just an anti-Valve group, they decided to shut it down.This was followed by the Left 4 Dead 2 DLC "The Passing", which brings the original survivors and the new ones together (well, three of them anyway) and "The Sacrifice" for Left 4 Dead, which lets players choose who makes the ultimate sacrifice and was preceded by a free comic. The latter update also made "The Sacrifice" and "No Mercy" available in the sequel, complete with the original survivors as the playable characters. Cue rumors that Valve plan to make the entire first game available for free in the sequel and more cries of "ruined forever!" Which they did.The game also received massive critical acclaim for both its Myth Arc style narrative - the parts of the story they don't tell you, as well as the interactions between the survivors - and for its emergent narrative, in which different aspects of gameplay combined with elements of randomness mean that every single time you play a new, funny story emerges.Please take a look at the character sheet to learn more about the characters and the Shout-Out page for countless pop culture references.
Absurdly Spacious Sewer: Has at least two, though both are nearly devoid of any geometry and only require the players to move in a straight line from the entrance to the exit.
Acceptable Breaks from Reality: Melee weapons would technically break after extended use in real life and Coach could never run for a while without being winded due to his knee injury and excess weight, but these things are ignored for the sake of simpler gameplay.
And, as each campaign in Left 4 Dead 2 is connected to the last, and your character still talks as if there were other survivors, in whatever campaign you're playing, this mode gives off the feeling that you were somehow separated from the other survivors between this one and the last one, but since there are also no longer any "normal" zombies anywhere, it suggests that something... else must have happened along the way, too.
Artistic License - Physics: the Silenced Submachine Gun has a little cloth strap dangling off its front, serving as a foregrip. When you reload the gun, tilting it this way and that, that little cloth strap continues to stick straight down perpendicular from the frame.
In the comics the military is merely useless instead.
That said, the military does act rationally, if harshly. At the end of The Parish they arrange a special helicopter for the 4 survivors because they are presumably carriers. On the other hand, they shoot normal humans who try to get past the barricades without any degree of contact without a second's hesitation.
When powering up a Merry-Go-Round (and alerting a horde of zombies) to get through to the other side of the carousel, the song that it starts playing is stereotypical creepy carnival music that's very slow-paced and ominous-sounding. Makes you question how well it did back when the carnival was still actually in operation.
Cryptic Background Reference: The only parts of the story that are completely laid out for you are from the single 4-chapter comic ("The Sacrifice"), and the short character bios that each of the Survivors get (neither of which are found in-game). The rest of the plot that's given to you will only be through random (often campaign-specific) character dialogue, about 99% of which isn't even guaranteed to trigger (usually requiring multiple play-throughs if you want to catch everything), or occasionally from significant pieces of the map, but most of all from the writings on the walls of different saferooms (and occasionally elsewhere) of other people who have passed through that area, describing bits of their experiences as messages to others, agreement or disagreement with what the military is/was doing, just how bad CEDA failed, how fast somebody changes into a zombie after being infected, and so forth, but not even those people are in 100% consensus about whatever's been going on, and nobody really has any idea what evenstartedthe whole thing.
Dedication: If you die during the finale you don't get to respawn, but as long as at least one character escapes, the credits will start with "In memory of [Player Name]"
Deep South: Left 4 Dead 2 starts in Savannah, Georgia and makes its way to New Orleans.
Determinator: Keith, if Ellis's stories are to be believed. The man has been inflicted with almost every injury one could think of (half of which are essentially fatal), and he not only survived, but was one of the first people out on a rescue chopper.
The Dev Team Thinks of Everything: In Dead Center, the opening of Left For Dead 2, when the survivors reach the elevator they use the brief lull to introduce themselves to each other. If somebody dies before this point, one of the other characters mentions the dead character's name.
In scavenge finales, if the players carry red explosive gas cans, then it can be used to fill up the necessary machine as well as the yellow cans used for these finales.
Did You Just Flip Off Cthulhu?: As in the first game, the best way to distract a Tank from beating on somebody is to get right up against him and melee him. Unfortunately, since he no longer focuses on downed survivors, it's not as necessary a tactic anymore, but it's still effective if he has a teammate trapped in a corner.
Dungeon Bypass: Guarding the doors and windows is all well and good, but more often than not the horde just crashes through a wall.
DVD Commentary: Like all Valve games, both Left 4 Dead games have a commentary mode, where you can play a campaign that contain commentary nodes which will play commentary audio from the developers. You're locked in Easy difficulty and zombies will ignore you. Naturally, you can't earn achievements this way.
Elevator Action Sequence: There are a few elevators and lifts to take much like this. The most prominent is the elevator in Dead Center's hotel, which breaks down when the building is set on fire, and forcing it open causes a crescendo event.
Everybody's Dead, Dave: The only non-zombies you hear in the game are the playable survivors, the (sometimes) unseen pilots and drivers who rescue you at the end of each campaign, the occasional psycho/weirdo, and occasional gunfire off in the distance.
Everyone Calls Him Barkeep: Coach. When the survivors introduce themselves to each other, Coach states that all his friends call him as such and that they (the other survivors) may as well do the same.
Rochelle lampshades this occasionally if Coach gets killed.
Rochelle: "Do you think Coach was his first or last name?"
Four Philosophy Ensemble: Nick as Cynic (pessimistic), Ellis as Optimist (naive), Coach as Realist (leader) and Rochelle as Apathetic (level-headed).
From Bad to Worse: Leading up from the first game, there is evidence that much of the urban parts of America are completely overrun and that the infected are changing even more; just a month after the first case.
There's a CEDA map in "Dead Center" with markings suggesting that the entire eastern half of the United States has been written off as unsalvageable, with the exception of New Orleans.
Hammerspace: If you have a melee weapon and are incapped (or a chainsaw runs out of gas), this is where the pistol comes from.
Heroic Sacrifice: The light chopper pilots were making repeat trips into the infection zone, getting infected for their trouble. They still kept the rotors spinning right up until the bitter end.
It becomes especially weird when you go to a playground & a theme park.
Hollywood Darkness: Valve uses a fog effect in some areas to mimic the Hollywood technique of "smoking the set", which conventionally uses a fog machine to help create atmosphere in "dark" areas. The fog catches the little light available, which makes everything slightly brighter, and allows viewers and players to see the silhouettes in the distance when they would otherwise be indistinguishable against the dark background.
Idiot Ball: The reason the Hard Rain campaign ends with you defending a fast food joint with a bright sign is that at the start of the campaign, while getting off the ferry, the survivors simply forgot to bring a flare gun with them. All four of them assumed that someone else was going to be carrying the gun bag.
Idle Animation: The infected alternate between leaning on the wall, sitting in despair, barfing up their guts (literally) and killing one another. The survivors alternate between stretching, wiping their faces, or picking their noses.
Incendiary Exponent: Every Special Infected can attack you whilst on fire. Hunters will actually do more damage while aflame.
The Uncommon infected usually boil down to this, being dressed in construction, hazmat, clown, riot, etc. gear.
All of the infected at the wedding in The Passing are dressed in fancy attire, including the Witch bride.
Possibly taken to its limit in the popular custom campaign Suicide Blitz 2. The finale takes you through a football stadium, and once you reach the middle of it, two Tanks in football gear run in from both ends of the field. It's hilarious, but the realization that even young, possibly college-age athletes in their prime fell to this plague is a bit disheartening.
Zoey: Heh. *sniff* Yeah. We always made fun of that part. ...'''BANG'''
Leitmotif: Every Special Infected gets two of their own tunes, one that plays when they spawn, and another that plays while they're attacking a Survivor.
Left for Dead: A regular occurrence in the rush for the rescue vehicle. With an incoming Tank that must not enter the rescue vehicle, this choice must be made often.
Not to mention what this game was named after.
Loveable Rogue: Nick has a somewhat shady (and probably violent) criminal past, and he starts out with a lone wolf-style attitude, but because of the circumstances he's in, as the game progresses, he's slowly forced to shed that attitude, and learns to trust and respect his teammates (well, respect MOST of them) and almost grows close to them, and sticks with them through whatever they go through. He probably has the most Character Development out of any survivors because of this.
It also helps that he's the character providing most of the game's Deadpan Snarker. He bounces some of the best lines off of Ellis because of this.
Made of Plasticine: It's not uncommon for the basic infected to be graphically dismembered by a shotgun blast, a few stray bullets, or being bashed with a rifle butt.
Man Child: Ellis, a goofy, happy-go-lucky mechanic who cheerfully espouses his love of everything redneck (like NASCAR) and believes his friend's wild stories of everything, ever.
Message Board: Saferoom graffiti really acts like this, although people who leave the saferoom probably don't return. Ever.
Metal Slime: The Fallen Survivor infected in The Passing campaign. They only appear once or twice, have as much health as a Witch, and will run away the minute you attack them. They also carry items like pills, pipe bombs, molotovs, and first aid kits, so killing them is always worth it.
Militaries Are Useless: An aversion. While the CEDA is quickly overwhelmed by the zombie invasion, the military is both far more ruthless and more efficient at dealing with it; the evacuation points of the army are still operational, and for what we know of it, they do manage to save people from the zombie invasion.
Musical Spoiler: Musical warning is given for when a horde appears, a tank appears, or when a witch is nearby. It also plays softly whenever any special infected are nearby, making those who know each one's theme music able to know one's nearby even without hearing them or seeing them.
Near Victory Fanfare: "Skin of our Teeth", a fast-paced, intense tune that plays when the rescue vehicle arrives.
Nick's description of the Tank fits it best: "HOLY SHIT! BIG FREAKING ZOMBIE!"
Night of the Living Mooks: Pretty much shuffles the Horde's character models at random. Also gives so much variety of appearances for individual parts of the zombie that the chances of seeing the exact same zombie twice is maybe 1:1000.
Non-Fatal Explosions: Zigzagged; while explosions from grenade launchers, pipe bombs, propane/oxygen tanks and barrels will deal lethal damage to any infected within range, they'll hurt survivors for maybe 5-10 damage at most on Expert.
Nostalgia Level: All of the first game's campaigns have been ported into the second.
Not Using the Z Word: Played straight and averted. The survivors call them zombies, but subtitles consistently refer to them as "infected" regardless of the dialogue.
Oh Crap: The first time the characters see a tank, they panic (every other time as well, but not to the same extent).
Coach: Holy shit! What is that?! Some sorta... super-ass zombie!?
At one point, they climb out of a sewer to find... a car yard. Full of car alarms.
Nick: Whoawhoawhoawhoa! Watch where you shoot!
Painting the Medium: The ending to the "Dark Carnival" has you activate the stage effects for a band that was originally going to play. The next two Tank cues then have a very distinct rock feel to them over the original orchestral.
Nick: Hate to break it to you, Coach, but your heroes lip-sync. There's a tape back here labeled "Finale".
Power Glows: Witches inexplicably cast a red light in darker areas where you would otherwise have a hard time noticing them.
The Power of Friendship: Literally. Nothing will get you killed faster than leaving your fellow survivors behind and trying to Rambo your way through the next level alone.
Previous Player-Character Cameo: The main appeal of The Passing is this trope. The survivors from Left 4 Dead assist you in the finale with cover fire and extra supplies. Bill, however, is dead.
Real Is Brown: Used for how a zombie would see the world. Players taking the role of the zombies in VS mode will see the world completely brown.
The "shooting the pilot" snafu in "Swamp Fever" counts as a running gag from the original game; "Crash Course" starts off with the survivors standing at the site of a helicopter crash — the news chopper from "No Mercy" — and the various possible dialogues make it clear that Zoey had to kill the pilot after he turned (to which Francis is very likely to snark at her over).
Scare Chord: One plays briefly with a piano when a Witch is startled.
Averted with the core campaigns, which lead into one another. L4D2 also retroactively applies this to the original game's campaigns with the addition of The Sacrifice and The Passing, connecting the story as a whole together.
Played straight with Cold Stream, which does not fit into the canon of the story and is considered a "what if" scenario. It is currently the only "official" campaign not designed by Valve directly.
Stereotype Flip: Rochelle may very well be the only black Depeche Mode fan you have ever met. Coach may be the only black guy into punk/hard rock band Midnight Riders.
Suspiciously Apropos Music: In "The Passing", you can play a song about leaving someone (by the Midnight Riders) near a Witch who was infected at her wedding.
Tattered Flag: The Sacrifice DLC campaign begins with the survivors trekking through a zombie infested dockyard that had been occupied by the military and FEMA expy CEDA with the camera prominently showcasing a tattered US flag flapping in the wind. Doubly significant because of the canon death of Bill, a Vietnam War veteran at the end of the campaign.
Technically Living Zombie: The infected might still even be curable, according to the military. This is most likely wishful thinking.
Terrified of Germs: Averted, the survivors don't mind being covered in zombie guts. Or fishing pills out of urinals.
Nick plays it straight.
"A little hand sanitizer and we wouldn't be in this mess." "A germ just wiped out the world."
"I am NOT jumping into the- screw it, let's go." (In reference to the sewer on The Parish.)
While some might think that this is only done to appeal to the largely male demographic, this is actually justified via genetics. The gene for immunity is strongly hinted to be on the X-chromosome, meaning that males only have to receive one immune X-chromosome from their mother to be immune, while females have to have one from both their mother and their father. Hence, the much smaller proportion of immune females to immune males.
The Tetris Effect: Play the game for a good hour or so. Close your eyes. See the zombie horde rushing towards you?
Wham Episode: In "The Passing", Bill is dead. You get to watch him die in "The Sacrifice". You don't specifically have to sacrifice Bill, but you do have to sacrifice someone.
What Happened to the Mouse?: The loose ends of the people that rescued the L4D1 survivors are tied up in the Sacrifice comic, they all turn, need to rally elsewhere, or can't stand the survivors. L4D2 shows or explains what happens to all in the next campaign.
Zombie Gait: How individual zombies walk until they see you.
Meta (Community/Developer/Supplemental Material) Tropes
Art Evolution: The higher polygon count and upgraded lighting effects compared to the first.
Bag of Spilling: Played straight in the beginning of Hard Rain. After being dropped off to the Burger Tank by Virgil, the survivors realize that they left their bag of guns on the boat.
Virgil: I'll drop the anchor just off shore, waitin' for ya. Signal at me when you get the gas. Nick: What are we supposed to signal him with? Ellis: Oh, there's flares in the gun bag. Nick: What gun bag? Ellis: You didn't grab the guns? Nick: Me?! Who died and made me gun monitor? Ellis: Pretty much everybody.
Bite The Wax Tadpole: The zombie hand on the cover is holding up 2 fingers in the same manner as someone in the U.K. would when telling you to do something unpleasant... Apart from the UK version, where the hand is photographed from the other side, making a "victory" sign.
Body Horror: The Special Infected have undergone horrible and probably quite painful mutations from Left 4 Dead to Left 4 Dead 2—the Smoker especially. The new Special Infected haven't had it easier, either; just look at the Spitter.◊
Character Filibuster: The other survivors have to tell Ellis to shut up whenever he rambles on about Keith (and Zoey in the "The Passing" DLC).
Deliberately Monochrome: After being downed and revived twice, you see the entire world in black and white, complete with blurry peripheral vision and red item highlights. If you're not healed, you will die. The developers included this because playtesters were frustrated when inexperienced players were repeatedly going down and delaying the group.
Dirty Business: In order to halt the spread of the infection and save what ever non-infected people they can, the military in The Big Easy made it their policy to gun down carriers (people who don't turn but can spread The Virus) by the hundreds, maybe thousands. Whether this makes them Anti-Hero or Knights Templar is open to debate.
Dummied Out: The "fallen survivor" uncommon infected, which was brought back(albeit with a very different ability) in the Passing.
Easter Egg: And in The Parish, going up the stairs of the store-made-safehouse, you can find a door with an orange light outline.
Gone Horribly Right: The result of Valve trying to squash the game breakers from the first game; melee shoving abuse and corner camping. The sequel added new special infected to discourage survivor players from corner camping and added running events where the survivors have to move in order to stop the event. However, this backfired greatly since most survivor players will now rush the entire time in every map and rarely stop, making it difficult for infected players in versus mode to land an attack on them.
Gorn: The damage modeling borders this, even more than the first game. Torso wounds gape, expose bone and can spill out the zombie's guts, heads may be only halfway destroyed, pipe bombs exploding a mob of enemies went from the first game's cloud of red to a shower of assorted body parts and intestines, and anything that catches fire will have a charred appearance by the time it stops burning.
It's Popular, Now It Sucks: Invoked and played with by the Midnight Riders. Near their last known concert site, a bunch of well-wishers and mourners lament the loss of the Midnight Riders... until a graffiti says they were safely airlifted out. Then the graffiti turns to angry "they sold out and were never good" insults.
Leeroy Jenkins: Mostly applies to newbies who keep making common mistakes, such as running ahead of everyone (which usually gets them killed and are too far away to be saved in time), angering a Witch without having the right gun for it (only shotguns can kill her instantly with a well placed headshot), or flinging Molotovs like a hot potato and setting other players on fire from it.
Oh, there's more. See the trope page itself for the huge list.
Let's Play: Both games have one on the Something Awful forums, with the first already archived and the second temporarily on hiatus.
Preorder Bonus: The baseball bat weapon, which spawned in the start of every single campaign and people who didn't preorder could still use the bat as long as a player on the team had preordered. When The Passing DLC was released, baseball bats now randomly spawn in the maps with other weapons instead of always being in the start.
Poor Communication Kills: This will literally be your game-ender online if you or the rest of your team fail to talk or at least call for help if being pinned by the infected, especially in Realism and Realism Versus modes where you can't spot each other with glows anymore. Lots of games have been lost due to people simply not speaking up.
Serious Business: Handfuls of people take the game very seriously and will scream at you or call a vote to get you booted if you do anything they don't like (not the Too Dumb to Live type player mind you). More noticeable in VS mode where people will yell at you for not saving them from the infected quick enough and/or yell at you if you don't do enough damage to survivors or just plain outright miss your attacks. note In fact, in most Versus games, when someone becomes the Tank, all the infected players put all their hopes on the Tank player and expect him or her to to kill the Survivors in one go. What most people don't realize that the Tank alone cannot kill the Survivors unless the players are extremely stupid and the Tank needs support from the other infected. If you're the Tank and get caught on fire or die without killing at least one player, expect most people to call you a fail Tank.
Sliding Scale of Continuity: The game is pretty firmly level 3 (Subtle Continuity), with the start of the next area being a direct result of what happened at the end of the last. For example: fueling up a race car to escape from a zombie infested mall only results in them abandoning the car when they reach blocked traffic, thus having to travel through a dilapidated carnival on foot.
Suffers Newbies Poorly: VS mode has a lot of these guys if you're new to the game mode. Teamwork is critically important and while you will get people who are forgiving of your mistakes, you'll get just as many people who want you gone. Naturally, you'll encounter less of these problems as your skills improve.
Take That: In the 2nd map of The Passing, when approaching the stairwell leading into the sewers, there's a sign that says the rest of the underground tour will be finished in the year 2010. Rochelle or Coach may quip about how the first phase is nowhere near finished and wonder how there can be a phase 2 already. This is a jab at the fan base that cried out how Left 4 Dead wasn't finished when Left 4 Dead 2 was announced.
The Virus: If you're... unlucky enough, you turn into a constantly crying, always-guilty Witch, a head humping horny midget, an acid spitting hag, a giant armed freak, an exploding fatass, get Gene Simmon's tongue, become a flying Parkour expert, or turn into the Hulk.
Artificial Brilliance: while the Special Infected can be quite stupid at times, it doesn't happen too often.
Most of the times, they are quite smart and are very wary of the presence of the players. Hunters and Boomers will always try to hide around corners or behind thick shrubs so that they can ambush the players. The two may also tag team players if a player is caught by a Smoker. Smokers and Spitters will attempt to run away if their attack fails and Hunters will escape by repeatedly jumping away if they are shot at from a distance. Generally speaking, the Specials all try to get to places that the survivors can't reach easily before attacking or after being spotted.
Tanks are now much smarter than in the prequel. They try to avoid fire the player makes, assuming the player sets the fire off too early. When they down someone, they will usually go chase the other survivors instead of just pounding one till they're dead and become a sitting duck. Though pounding one of the survivors to death is occasionally a smart move and somewhat terrifying, there's a reason you were never encouraged to do that in versus.
The Common Infected themselves show signs of this - instead of running straight towards the Survivor, they tend to run around in circles, avoiding bullets while attacking the Survivors to the sides or even the back.
Artificial Stupidity: Although not too horrible, the Survivor AI has many infamous quirks. This is a great reason to play the game with actual people. See this YouTube video as a hilariously shameful example from around release.
The AI seems to have been improved since the first game, though some of the achievements cause it trouble. Of particular note is the "Sob Story" achievement, requiring the player to complete a stage without killing a Witch. The AI is not remotely suited to sneaking missions.
The Chainsaw Massacre mutation amplifies the survivor bot's stupidity to new levels. They will either run ahead or lag badly behind and not do too well in saving you from special infected. This was corrected later causing the AI to rarely stray far from players, but they are still have issues.
A similar case also happens for Smokers. In the first game, the survivor bots would usually be really quick in saving someone caught by a Smoker. In the sequel, they now will sometimes wait until you take damage before they free you.
Whenever you encounter a Spitter, bots will make no attempt to avoid their acid until they've already stuck their feet in it.
If the bots get close to the safe room, they make a beeline for it and stay there regardless of the threat level in the immediate surroundings. This can lead to you getting pounded to death by a Tank and swarms of infected while the bots cower in the safe room. Doubly annoying considering that in most other situations, the bots are too dumb to keep up with you without you constantly stopping and looking over your shoulder.
Bad Boss: The Director in Versus mode. Between showering the survivors with first aid kits and often not bothering to send a horde after a boomer attack, it clearly hates the Infected players even more than the Survivors.
Black Out Basement: The official campaigns do a good job of averting this in favor of Chiaroscuro lighting, but all bets are off with custom campaigns (one of which is titled the exact name of the trope).
Blatant Item Placement: Zigzagged. A lot of guns are found by dead survivors, Whitaker's gun store, security room gun lockers, or a suitcase that contains money as well as pistols, explosive items are usually found near generators, and axes, crow bars and guitars spawn where they'd be used. But on the other hand, a lot of items spawn in very illogical places. There's massive heaps of Ammo in meeting rooms, sewers or in a certain bathroom, pills can spawn in urinals, a motel is full of jars of bile and pipe bombs, the store next to Whitaker's usually has a Molotov. There are entire lockers full of Molotovs or Pipebombs in various buildings, and just past a wedding are several tents full of guns. Whispering Oaks has a bizarre number of guns for a kids theme-park, explosive ammo and incendiary ammo just spawn in the back of trucks, there's almost no reason for a katana to spawn anywhere, the list just goes on.
Mercilessly averted with the Tank, which receives the same damage from headshots as being shot anywhere else.
Bottomless Magazines: The players must reload, but they've endless ammunition for their sidearms and supply caches provide infinite replenishment for your main weapons.
Exaggerated in the Gib Fest Mutation gametype, which gives all four survivors an M60 with infinite ammo.
Calling Your Attacks: Played straight by survivors throwing grenades, invoked with the special infected's vocalizations giving them away.
Camera Perspective Switch: The game is mostly played in first person view, but the camera will switch to third person view when the player is doing an action or is pinned by a special infected.
Chandler's Law: The Director AI pulls this quite frequently: stay in one place too long instead of advancing and you'll get a bunch of Special Infected coming at you.
It's also more likely to send a Zombie Horde at the Survivors at any given moment the slower they're progressing through the level. This can be something of a vicious cycle when playing on Expert.
Chekhov's Gun: In the first chapter of The Dark Carnival campaign, a jar of boomer bile will always spawn in the same spot. Almost no other jars spawn for the rest of the entire campaign. If you keep that jar till the end of the fourth chapter, it can be used to almost completely bypass an incredibly tough gauntlet right before that chapter's safe room.
Averted with the survivors. When seriously injured, you run slower, jump lower. After taking pain pills, or having just been revived by a teammate, your health is constantly dropping, and at 1 HP you slow to a crawl. If your health gets taken all the way out and you're not on your "last down", you drop to the ground, only able to use pistols, and slowly bleed out until you die or are revived by an ally.
Played straight with the common infected. Play long enough and you'll see a zombie run up to you that has had both of its arms shot off. (What does it plan to do then, bite you?)
Even if one of them explodes after their life goes from 1 to 0, it's mostly Justified with the Special Infected, who obviously are extremely aggressive and have little-to-no self-preservation instinct left. Barring a few Specials who will duck behind a wall if they're not ready to attack you yet (before attacking you later instead, of course), they are going to come after you no matter what happens to them until one of you is dead.
Damage-Sponge Boss: Tanks, full stop. Four Survivors starting a level have a group total of 400 HP. On Normal difficulty, the Tank has 4,000.
Daylight Horror: Daytime segments don't just change the lighting, but the behavior of one of the Special Infected. Witches normally sit in one place at night, but during the day they wander around.
Death Course: The finale to The Parish differs from the others tasks the survivors with racing across a bridge to a waiting military helicopter while fighting off continuously-spawning waves of zombies.
Death Is a Slap on the Wrist: Dying does not mean you are forever gone from the game. You will just respawn in a closet, come back in the next map, or get revived on the spot from a defibrillator. Versus and Realism mode prevents you from coming back until the next map and dying during a finale on any mode gets you Killed Off for Real.
The grenade launcher can clear out hordes with one well placed shot, make most special infected stumble (making it great to free pinned survivors without worrying about accuracy), and a direct hit to the Witch can make her stumble and buy you time to get away or kill her quickly. The difficulty in using the weapon is you have to reload after every shot (and each reload takes about 4 seconds) and you can't get more ammo for the grenade launcher. Unless you are skilled enough, you may cause lots of friendly fire damage to yourself or the team. You will be using your pistols or melee weapons a lot to make up for the grenade launcher's weaknesses.
It is entirely possible to counter every single Special Infected's pinning attack (smoker's tongue, hunter's pounce, Jockey's riding, etc) with a well placed shove, shot or slice. However, the window for you to perform these actions are measured in a fraction of a second, but it feels completely awesome to do so.
The Tonfa is the fastest melee weapon out of the entire melee weapon set. It swings very fast, but it has an extremely short reach and swing arc, which makes it difficult to consistently hit zombies that are swarming you.
Difficulty Spike: The jump from Advanced difficulty to Expert is huge. On Advanced, a common infected will deal 5 points of damage if they hit you in the front whereas they do 2 damage on Normal and 1 on Easy. On Expert, common infected can cause 20 points of damage in the front. Hunters can slice you for up to 40 points of damage, dealing the most damage out of all of the infected on Expert except for the Tank, who can instantly bring you to incapacitation in a single strike. Not to mention that Witches, which previously incapacitated you in one hit as well, now just flat out kill you.
The Director Is A Cheating Bastard: Unusual, in that the Director is supposed to be continuously tweaking the challenge of the game up and down based on how well the players are doing. However, on Expert, it's moments of mercy are extremely brief.
This goes for the survivor bots too, as they have aimbot accuracy, and cannot directly cause friendly fire(being able to literally shoot through others). It works, as a half-decent human player is still more efficient overall (due to other factors like bots not being able to use grenades or any particular strategy beyond shooting things), yet a team isn't completely screwed if a player leaves mid-game.
Under certain conditions, survivor bots will grab items through walls. Players can't.
L4D2 has been accused of adding a degree of Fake Difficulty by multiple special infected spawns in campaign modes, but these are glitches... The Hard Eight Mutation notwithstanding.
Any special infected (other than witches or tanks) can slash you with their claws if you manage to shove them. No "attacking while staggering" animation or anything, blood literally just pulls itself out of your chest.
In co-op and other modes where the special infected are AI-controlled, the specials can spawn inside the safe room at the end of the level, leading to fun times. In versus, where the specials are human-controlled, you cannot spawn in the ending safe room.
Escort Mission: Played with with the "Guardin' Gnome" achievement, which is earned by winning the garden gnome from the shooting gallery in Dark Carnival and carrying it through the rest of the campaign and onto the rescue chopper.
Exploding Barrels: Gas cans, propane tanks, oxygen tanks, boxes of fireworks, and actual barrels in the Sacrifice campaign.
Falling into the Cockpit: Versus mode, infected team. While a player can run through the campaign mode to build up their survivor skills before going in, infected players have to learn it all on the fly for their randomly assigned characters.
Fake Difficulty: The Hard Eight and Special Delivery mutations spawn Special Infected at an increased rate, which is a good challenge for players who know how to deal with each Special and move along. Unfortunately, Spitters tend to be spammed, especially in tight spots, which forces you to either run through its acid or wait it out (a terrible idea with the constant stream of powerful zombies). And if you do the latter, chances are another one will spawn immediately after it dissipates.
Fetch Quest: The Streets chapter of Dead Center require the survivors carry a sixpack of cola, carrying the gnome to the helicopter in Dark Carnival gives players an achievement, and there have been a few Mutation gametypes requiring the gnome.
Game Mod: From adding extra custom campaigns to correcting scripts like bot behavior or gun realism, and including changing the flashlight's texture so that it becomes useful or funny, these were add-ons were always popular in the game. The Workshop update made them even more so due to the ease to install and manage them.
Genre Savvy: Nick asks the group, after they reach the hotel elevator in Dead Center, if anyone has been bitten.
Nick: Did anyone get bit? Isn't this how this works?
Wrong Genre Savvy: The survivors are immune, the disease is airborne, and quite frankly there's a pretty low chance of them not getting bitten anyway.
Goomba Stomp: Jumping on a common or uncommon infected's head is instantly fatal. Doesn't apply to special infected. Physically being on top of a zombie counts as a stomp, thus an instant kill, which leads to a hilarious moment where you can literally walk over a zombie lying on the ground and kill it from just stepping on it.
Gravity Barrier: Keeps you away from a zombie breeding ground and to keep you moving along to your safehouse.
Griefer: Per GIFT, you're guaranteed to come across them in public matches. The most common type of griefer are players that shoot their own teammates to death, which is extremely common on Expert difficulty games due to the sheer friendly fire damage.
Playing as the infected is basically griefing the survivors as the goal of the game. The griefers are getting their kicks from the game itself most of the time!
The Room for One Mutation gametype defies the normal logic of the game by only allowing one survivor to escape and encouraging team killing.
Realism mode is a setting independent of the standard difficulty settings. This mode removes all the auras allowing you to locate other survivors, items, and infected which are pummeling other survivors. Commons take less damage when shot anywhere except the head, and survivors only respawn at Safe Rooms. It can also be set to Expert mode, which gives you an achievement if you manage to survive. One odd quirk of the mode: the magnum still instantly kills ordinary infected with body shots, which greatly increases its value; an early magnum can make a big difference in survivability.
Apparently, Realism mode will be nothing compared to Ultra Realism Mode
Health/Damage Asymmetry: Each of the survivors has up to 100 health. Besides The Boomer and The Spitter, all special infected have at least twice as much, with the tank starting out with at least 4,000, yet the survivors can pick off special infected with a few shots of the right gun, and special infected do damage slowly over time. Subverted on Expert mode, when it's just the damage that is symmetrical. They will happily kill you off if your team mates are distracted.
Hell Is That Noise: Every single type of Infected has their own distinct sound/musical cue to warn you of their arrival, including a few who will switch from low growls to all-out screams or roars as soon as it has one of the Survivors in its line of sight. Because the Survivors can be overrun very quickly on just about any difficulty if they aren't being attentive enough, listening for them is so essential that you almost can't play it without the sound up reasonably high (which doesn't help a whole lot with the Jump Scares).
He's Just Hiding: Literally. Whenever one of the guys die, they're found later trapped in locked closets (or respawn in the next saferoom). It was meant to reflect how survivors get rescued in zombie films. invoked
Averted in the final chapter of each campaign after the rescue vehicle has been summoned. Dying means you get Killed Off for Real.
Hitbox Dissonance: Hitboxes for hunters and jockeys move in front of them when they pounce, which makes them extraordinarily difficult to knock out of the air with even the slightest bit of lag. Compounded further by how little time there is to stop a jockey pounce.
This game somehow just has inferior collision detection. It isn't common, but it certainly isn't rare to hear the impact and see blood fly from a zombie you just smacked in the face with a crowbar just ignore it and continue anyways...Even when playing offline where lag couldn't account for it.
Hold the Line: Occurs in all crescendos and finales(except a couple in the Parish) as well as survival mode.
Hyper Awareness: meta example. The best players exhibit this, being aware of all the directions from which infected could attack and keeping their eyes (and ears) open for incoming specials. In comparison, the AI bots (as mentioned above) are Lazy Backup with a horrific case of Selective Obliviousness.
Inexplicable Treasure Chests: The lockers in The Passing. There may a justification for when they're full of pain pills or even adrenaline, but why do people need that many pipe bombs and molotovs? And why are they found in offices, underground tours and weddings?.
Infinite Flashlight: No matter what you have equipped, you'll have a light to see your way through. It has a handy-dandy on/off key for when you want to be stealthy as well. Modders have made add-ons available where the light is made better or goofier.
Your vision becomes monochrome with red halos for items if you're incapped twice without using a medkit.
A variation also occurs with a lightning storm in Hard Rain. When the storm is passing overhead, players' microphones are automatically quieted, to the point the players will literally have to shout to be heard by their teammates.
Invisible Wall: Only the Infected in Versus mode will run into them, and if you get close enough they stop being invisible... instead they become labeled "wrong way!"
It Can Think: The Director is actually a rather well working AI system. Depending on the difficulty, it will decide when to place more zombies to hinder your efforts. On Expert difficulty, it just wants you dead and doesn't pull any punches.
Killer Game Master: The AI director. Particularly on Expert mode, when he stops even pretending he doesn't hate your guts.
In Left 4 Dead 2, there are some maps where the infected charge out of the safe room, or very close to it. However, the director will stop the attacks when all four players are in the room but with the door still open (but existing infected will still charge).
Level In Reverse: The campaign Hard Rain has the second half be the levels of the first, played backwards and with a monsoon in full effect, obscuring vision and dialogue.
Limited Loadout: You can carry one of each item that occupies a slot, such as the following:
Primaries; Shotguns, Automatics, and Sniper Rifles. The 2nd game includes a Light Machine Gun and a Grenade Launcher.
Secondaries; A pistol which can be dual wielded with another. The sequel adds the Magnum Pistol and melee weapons.
A kit-based item; The game's token Medkit. Two more items were added in the sequel: A defib and two different ammo kits.
One grenade; Pipebomb, a Molotov Cocktail and the Bile Bomb from the sequel.
And a temporary health item; The first game only sported Pain Pills, while the sequel added another use for the slot with Adrenaline.
Made of Plasticine: Because of how melee weapons work, it's entirely possible, and really easy, to carve through a Zerg Rush with, let's say, a baton. Also, hitting a special infected with a frying pan will kill them in one hit, except for the Charger, who takes two hits, and the witch/tank, who are Made of Iron.
Mini-Game: "Dark Carnival" has 3 games for you to play, which are the Shooting Gallery, Test Your Strength, and Whack-A-Mole with the park's mascot! They each are tied to an achievement as well. They also alert a horde of zombies if you successfully complete any one of them.
Mook Chivalry: The "Last Man on Earth" mutation makes it so that Special Infected (who's clutches you would normally need a teammate to escape) back off once they've taken off your first health bar. They're not as kind the second time around, however.
Jockeys and Hunters may sometimes decide to stay where they are and slash you the second you get up, which may cause death due to your health being so low after getting self revived.
Muscles Are Meaningless: The Witch is a small girl with relatively thin limbs (apart from the vicious claws)... limbs with which she can knock you down/kill you outright faster than any other Infected. Including the muscle-mountain Tank.
My Rules Are Not Your Rules: AI-controlled infected can spawn anywhere, melee while stumbling, climb things player-controlled infected cannot, and AI-controlled hunters even have a lunge move players cannot perform.
Occasionally averted in Expert and Versus matches when one survivor staying in the saferoom with the door closed can be the difference between success or failure.
There are also a few jarring situations in which you have passed a Point of No Return and cannot go back and help your teammates. This just reinforces the original lesson, since you are forced to soldier on short-handed.
This spawned the meme of Karma Charger, where a random Charger would come and pounce on you if you ever leave the main group. Fittingly, the AI director prioritizes lone wolves who ditch their friends, and would actually spawn a Hunter to deal with them. Of course, this lead to players finding ways to singlehandedly counter said "karma".
Nerf: In the original, players could "shiva stack" (wait in a corner or secluded room, all bunched up, and repeatedly melee). This made it nigh-on impossible to extricate them with anything other than a tank. Left 4 Dead 2 stopped stacking with the introduction of the Charger and the Spitter.
Melee weapon damage to Tanks has been nerfed. Damage is now 5% per hit instead of 10%, which means now that survivors will most likely have to resort to kiting now instead of everyone running up to a Tank and smashing him with four Frying Pans Of Doom.
And the shove motion itself has been nerfed with the addition of fatigue: do it too many times and there starts being a delay before you can do it again. This punishes the fact that you can get completely surrounded and need to shove your way out.
Also, auto-spawning in Versus finales being removed made it more enjoyable for the infected team and more difficult for the survivor team.
Mood Whiplash: Happens quite often, thanks to the automatic in-game dialogue.
Lone Gunman takes it Up to Eleven by surpassing Expert damage even on Eas y(ANY damage at all is game over on Expert Lone Gunman), allowing only one survivor armed with only a magnum and grenades, and spawning Boomers constantly.
TAAAAAAAAAAAAAAAANNNK!!! plays it for fun, by removing AI-controlled special infected and having players only be survivors or Tanks. This can actually make the game much easier, as survivors can just run like hell through the level without having to worry about being grabbed by a special.
Obtaining the "Strength In Numbers" achievement. To earn this, you have play Team VS or Team Scavenge with a group of your friends and beat the other team who are random players that are friends with each other. The catch? There will always be one team who will all Rage Quit and screw over the other team out of earning the achievement. On top of this, Team VS/Scavenge is hardly used at all since most people prefer public games where it is easier to set up and get a game going more quickly. With rage quitting and people not playing these game modes, the achievement is pretty much unobtainable without boosting.
No FEMA Response: CEDA tries to respond to the "Green Flu", but gets overwhelmed. Inevitably, every time the Survivors try to get to a CEDA evacuation point, it'll be destroyed with nothing but corpses to show for it, and they'll end up having to escape another way.
Non-Standard Game Over: During The Sacrifice's finale, if three of the survivors are killed, the level ends in a failure and you have to restart since you need at least two people alive for the final part since one person has to sacrifice themselves to restart the bridge and the other person has to be alive so they can escape.
Nothing Is Scarier: hearing a sobbing Witch and knowing she's close and you have to be careful or you'll startle her and she'll screech and try to rip you apart - and sometimes you just don't find her...
This is even more scary in the infamous Hard Rain campaign. It isn't bad enough to have 20 witches, it isn't bad enough to have them walk around, it isn't bad enough that all but three of the Special Infected can push you into one (and will appear absolutely out of nowhere), and it also isn't bad enough to have to fight tanks during this, but they also had to throw in the sugar cane fields (where your vision is reduced to about 2 feet in front of you).
And then it gets even worse on the way back through! Whenever the storming starts up, all the witches in the area will HOWL IN RAGE yet the odds of you actually running into one are pretty low. This continues right up until the finale, and you can never tell if that howl is on the other end of the level or just around that corner...
It doesn't help that the sounds made by the storm can resemble startled witches.
Forget Witches, sometimes you hear a special infected or its musical cue long before you see it or you know it's around the corner but don't want to be the guinea pig. The worse still, is when the Tank music starts playing but takes its time finding you so players are left frantically trying to spot it whilst trying to stick together or rethink their plans.
The worst scares you can get in Left 4 Dead 2 is in the mutation The Last Man On Earth, where it's single-player with no bots, and no common infected. It can get very eerie walking through the level alone while hearing the growls of special infected sneaking up on you, and since you're alone they are far deadlier.
What's even worse than that is the fact that the single character's vocal script is unchanged, meaning that they talk to thin air - even taking to specific survivors who aren't there anymore.
Obvious Rule Patch: VS mode's scoring was altered to be more close and fair between teams. Left 4 Dead had scoring be sorely based on who made it to the safe room plus a multiplier and if a team got killed beforehand, their score would be a lot lower. Left 4 Dead 2 has the score be purely on distance traveled so that you still had a chance of catching up if you didn't make it to the safe room.
Explosive ammo was removed from VS mode after some time due how easily survivors could stop attacks from the infected players with it. Defibrillators were also given a 25 point penalty for its use in VS mode so survivors are punished for having a teammate brought back to life in a way.
Parachute in a Tree: Corpses of paratroopers hanging from trees are frequently found. Upgraded weapons can be found on their bodies.
Headshots with Tier One weapons leave the head intact.
Randomly Drops: Hazmat uncommons (Dead Center and the Sacrifice) with bile jars, riot cop uncommons (the Parish) with tonfas, and fallen survivors (the Passing) with random items.
During the holiday season, gift boxes were randomly dropped by special infected in VS mode, linked to an achievement and a Steam sale raffle.
Regenerating Health: Inverted trope. Pills, adrenaline and getting picked up from incapacitation add a temporary buffer of XX health to your HP (differs from action to action), which disappears as time goes on.
Played straight with the Healing Gnome mutation. All health related items are removed from the maps and the only way to heal is to hold a special gnome that regenerates health as long as you hold it. Of course, this also reduces the amount of firepower the team has.
Lampshaded with the two Expert-related Achievements: What Are You Trying To Prove? and Still Something To Prove. Both you get for completing all of the Maps shipped with the game, on expert.
Sequel Difficulty Spike: 2 has many more spawn points for hordes, discourages camping, it's new special infected are even designed to punish survivors that stay too close to each other, rolling crescendos are much more challenging than the regular ones, and Realism adds another level of challenge even to the Expert difficulty.
The Passing and The Sacrifice DLC campaigns are much harder than others in spite of being shorter.
And in most every campaign that has been ported over from 1 to 2, there are alterations to increase difficulty. In some cases this is simply to adjust for the new gameplay elements, but they overdo it in some instances.
Most notably in the Terminal of Dead Air, what was once a panic event was upgraded to a Rolling Crescendo. However, the developers did not remove the normal crescendo event at the beginning of the level, resulting in this one having two crescendos, with one being one of the hardest in the game (you have to cover a lot of ground unlike in Dark Carnival).
Sound-Coded for Your Convenience: Major gameplay-changing events(horde attacks and tanks or witches being startled) change the music. Special infected spawning are accompanied by their unique theme(except in Versus) and their vocalizations give them away; especially for players using surround sound.
Speed Run: How some players play Versus mode as survivors.
Super Drowning Skills: Any map that has a river in it. Unlike the first game where being underwater too long would drain your health eventually, being submerged will instantly kill you.
The only exception is when the water is knee-height, and getting incapacitated puts you below the surface. After a moment, however, you start taking a reasonably large amount of extra damage (aside from the automatic bleed-out damage) until you either begin to get picked up, or you die.
Also applies when crouched underneath the water in the finale area of Death Toll (originally from the first game).
The water in Left 4 Dead 2 is so fetid that it will kill an infected that's in ghost mode. Causing their corpse to pop out of thin air, natch!
A few specials can cause this singlehandedly: tanks (natch), chargers, and (if your team is spectacularly incompetent) hunters.
Averted with the Witch, who is programmed specifically to only be aggressive towards one Survivor. Not that things don't go Off the Rails anyway.
Unique Enemy: Each campaign in L4D2 has an "Uncommon Infected" unique to it:
Dead Center has infected CEDA workers, whose Hazmat suits render them impervious to flames. There is also a zombified Jimmy Gibbs, Jr., who is also immune to flame, can obscure vision with motor oil, and won't be sidetracked by pipe bombs or Boomer bile.
Coach: "That zombie's got armor.." [beat] "I want armor!!"
Inverted in that some uncommon do carry usable equipment, but (being zombies) never actually use it.
Unwinnable by Mistake: There's a bug in the collision detection of the rescue boat that ends Swamp Fever and Hard Rain; depending on where your character is standing, this can result in them drowning as it sails out from under them. It is both depressing and hilarious to be boatmurdered in this way.
Video Game Cruelty Potential: There is just something so fun about jumping on top of a lone survivor as a Hunter, laughing in delight as you tear them apart, knowing they're completely and utterly helpless.
The VS mode is based around being as cruel as possible, as it actively encourages you to take notes during your own Survivor playthrough and consider when is the worst possible time for your particular special infected to appear, and to use it when it's your turn to be the zombies.
Violation of Common Sense: Downing a whole pack of pain pills at once would be fatal in real life, but somehow is a good idea if you're low on health.
In the zombie apocalypse, TRUE survivors don't even need to remove the cap to swallow a whole bottle of pills!
If you get mobbed by common infected, setting yourself on fire with molotovs or blowing yourself up with a grenade launcher will usually clear your space a LOT faster than to keep shoving them away or trying to hack at them all with melee weapons. You'll suffer self inflicted friendly fire damage, but that will be small compared to trying to clear out zombies invading your space without the said methods.
There are some cases where team killing is actually justified. If someone is about to die and there's nothing to heal with, players will usually kill the wounded survivor and then let them respawn in a closet or revive them with a defibrillator: both methods bring the Survivor back with 50 points of health. If no one speaks of this and do the deed, they could be mistaken for a Griefer.
Melee weapons always do 5% of a Tank's maximum health per hit (meaning 20 melee hits will kill them). This doesn't amount to much on lower difficulties, but it's certainly a lot of HP on higher ones. Obviously, trying to get close to a Tank when it can instantly incapacitate you is usually a bad idea, but being able to deal about 1,000 damage in 2 seconds without using ammo is something worth noting.
We Cannot Go On Without You: If there are any bots on the team in any non-Versus mode, you'll have to start the level all over again if all the human players are dead, regardless of if there is a bot player alive. It becomes mind-boggling when playing against a team of bot Survivors in versus mode and they are capable of moving through the level on their own without the guidance of a human player. Fortunately, there are Game Mods that fix this.
What the Hell, Player?: Shoot one of your fellow survivors, and they'll call you out for it with scripted responses.
Or trigger a few car alarms in the impound lot in the Parish:
Coach: WILL YOU STOP SHOOTING THE GODDAMN CARS!?
You Have Outlived Your Usefulness: Special Infected which are stuck or otherwise unable to catch up to the Survivors will occasionally be killed off by the Director, with the death noise often being faintly audible to human players.
Infected players can manually trigger this when they are at a certain distance behind the survivors, allowing them to skip the respawn time that would happen if they jumped off a cliff instead.
You ALL Look Familiar: The basic infected actually have a small number of basic models but are made to look different with various filters, like clothing and blood spatter. The Unique infected all look exactly the same since they wear uniforms and some of the Bosses have two models in the second game (the boomer has a female version, the Witch gets a one off version wearing a wedding dress in the final campaign), but only one in the first.
Zerg Rush: The AI director will send these at you at random, when a boomer vomits on you, in pre-programmed Crescendo Events where you're forced to make a ton of noise to continue moving, or if you accidently set off a car alarm, or whenever he's bored, which isall the time. The normal infected also like to rush pipe bombs because of the smoke detector alarms rigged to them, and Boomer bile (both regular and purified) for obvious reasons. It is also possible to use a bile jar on a Tank, and there is an achievement for it.
Abnormal Ammo: Frag or incendiary ammo boxes, which provide one magazine of this before switching back to regular rounds.
A.K.A.-47: As with the second game, though a few guns, both old and new, are now referred to by their real names.
An Axe to Grind: One of the most common melee weapons is, understandably, the ubiquitous fire axe.
Awesome, but Impractical: The minigun and mounted M2 machine gun, which can shred oncoming hordes and tanks like no other, are never positioned so they can effectively cover more than two of the generally five or so directions that zombies can come from in official maps. Additionally, the M2 is almost impossibly rare in comparison to the previous game's minigun, only showing up in two finales out of six.
The M79 grenade launcher, which requires much practice to use effectively – that is, kill as many infected as possible without blowing your own team up in the process.
Batter Up: Among the melee weapons, there are baseball bats and cricket bats. Sometimes a survivor will say this when they grab one.
Bottomless Magazines: For gameplay reasons, sidearms have infinite ammunition. They don't do as much damage as primary weapons and they share a slot with melee weapons, which don't have any limit either with one exception. Also, they're the only weapons you can use while incapacitated and if you're holding any melee weapons, you'll temporarily get one basic pistol until you're back up again.
Two mutations also employ this: "Chainsaw Massacre" gives the survivors infinite-fuel chainsaws, and "Gib Fest" gives them infinite-ammo M60s.
It is possible for Gib Fest games to glitch and spawn any weapon normally. Extremely rarely, it is possible to find a Grenade Launcher. Because of the one-shot nature of the thing in normal gameplay, anyone who finds one in Gib Fest will quickly notice it has no firing cooldownnote The weapon's long reload was meant to be it's cooldown, meaning once Gib Fest removed it's reload requirement your rate of fire is only limited by how fast the script replaces your ammo. Much hilarity ensues.
Chainsaw Good: The chainsaw has peerless damage dealing abilities, but has a fairly long starting time, only 60 seconds of "fuel", provides 50% damage resistance to common infected, and is replaced with a single pistol when it runs out of fuel or the user is incapped. The Chainsaw Massacre mutation is all about chainsaws: the only weapons that spawn are four chainsaws in the saferooms. They happen to have unlimited fuel.
Crowbar Combatant: Yet another option for melee fighting. It's about as common as the axe.
Guns Akimbo: All characters can find and dual wield a second 9mm pistol for extra ammunition in the magazines.
Hyperspace Arsenal: Generally averted, except for one peculiar instance. If a survivor drops their handgun for a melee weapon, they will produce another handgun when they are incapacitated, which disappears as soon as they are hauled back onto their feet.
Katanas Are Just Better: Played with. Damage-wise, Katanas in the game aren't any better than other melee weapons due to all melee weapons doing the same amount of damage to zombies. The advantages the katana has, however, is long reach and medium swing speed. The "Four Swordsmen" mutation is all about these, being the only weapon available.
Kill It with Fire: Molotov cocktails, gas cans, and incendiary ammo packs. Very useful against Tanks and Witches, as not only does it deal continuous damage until death (or the Tank wades into a body of water), it slows them downnote A Witch will only run as fast as a healthy Survivor, and a Tank slows down to an injured Survivor's pace.
Ludicrous Gibs: Pipe bombs, the M60 and explosive ammo produce this from common infected in 2.
The "Gib Fest" mutation amps it up to extremes by only having weapons that cause this. Namely, the M60. With a Magnum for when you're incapacitated or when you want a little more precision. The AWP produces the same results as a single M60 bullet.
The Musketeer: It's possible to have a melee weapon as reserve instead of a sidearm. Certain mods give them their own unique slot.
Ranged Emergency Weapon: Downplayed with the pistols. Despite being outclassed by primary weapons, they're rather decently accurate, damaging and fast-firing unless you're incapacitated.
Rare Guns: The Desert "Cobra", SPAS-12 and SCAR-L in Left 4 Dead 2. The starting pistol, a SIG Sauer P220, is also stated in the commentary to be extensively customizednote overall a P220 with the barrel and slide of the compact P228, and a custom two-tone finish, as is the Glock.
Shooting Gallery: In Left 4 Dead 2's "Dark Carnival" campaign, you can stop to participate in a shooting gallery whose prize is a lawn gnome; carrying the gnome through the end of the campaign nets you an achievement.
Short Range Shotgun: Averted. The shotgun's a viable weapon choice, even at a reasonable distance.
Sticks to the Back: Every weapon and inventory item except pistols (they get holsters), pills/adrenaline, and grenades, which all go on the survivor's belt.