"'X' is the first generation of robots which contain an innovative new feature — the ability to think, feel, and make their own decisions. However, this ability could be very dangerous. If 'X' were to break the first rule of robotics (a robot must never harm a human being), the results could be disastrous and I fear no force on Earth can stop him. Approximately 30 years will be required before we can safely confirm his reliability. Unfortunately, I will not live to see that day, nor do I have anyone to carry on my work. Therefore, I have sealed him inside this capsule, which will test his internal systems until his reliability has been confirmed. Please do not disturb the capsule until that time. 'X' possesses great risks as well as great possibilities. I can only hope for the best." September 18, 21XX T. Light
~ Message from Dr. Thomas Light, intro to Mega Man X on the SNES
In A.D. 21XX, War Was Beginning...Mega Man X, the Darker and EdgierSequel Series to Capcom's Mega Man (Classic) series, follows the exploits of the original Blue Bomber's future successor.As his Magnum Opus, Dr. Thomas Light created Mega Man X, a robot with a specially-designed "Suffering Circuit" that gives X the ability to decide right and wrong for himself. Dr. Light sealed X inside a capsule designed to run ethics testing over the course of 30 years to prove to the world that X would not turn out evil (since the conclusion of the Doctor Wily Incidents caused great fear of humanoid robots). A century later, archeologist and scientist Dr. Cain unearths X's capsule and soon becomes astounded by Dr. Light's engineering miracle. He decides to mass-produce a line of robots based on X — "Reploids" — but glosses over the fact that he doesn't fully comprehend Dr. Light's work. What Could Possibly Go Wrong?Soon after their activation and deployment into the world, some of Cain's mass-produced Reploids develop bugs and glitches that cause them to go mad and become disobedient, due mainly to flaws in the mass-produced Suffering Circuits created by Cain. These malfunctioning Reploids become known as Mavericks ("Irregulars" in Japan). To combat the increasing Maverick menace, Cain helps to create the "Maverick Hunters", a group of advanced Reploids authorized to use force in apprehending or outright stopping their violent brethren. Cain's first creation, a Reploid named Sigma, becomes the leader of this group.Cain's work backfires again when most of the Maverick Hunter group, including Sigma, turn into Mavericks themselves. Why the others turned, we have no idea, but Sigma turned soon after getting into a fight with "Zero", a mysterious and insane robot of similar capability to X but of unknown manufacture. Sigma's defection heralds the beginning of a massive war between Mavericks and humanity — and since he feels responsible for the Maverick outbreak, X decides to team up with Zero (repaired after having his "brain" destroyed by Sigma, which makes him useful to the Maverick Hunters) and put a stop to the war.In terms of gameplay, the series has the same basic formula as the Classic series: you choose levels in no particular order and gain weapons from defeated bosses; you use the weapons in an Elemental Rock-Paper-Scissors system against the other bosses; lather, rinse, repeat. The X games have a much more aggressive playstyle than the Classic series due to the existence of Video Game Dashing and Wall Jumping. The games' maps have a much bigger and more open design than the Classic series' maps to accomodate the new playstyle.The series saw several sequels on the Super Nintendo, PlayStation, Sega Saturn, PlayStation 2, and Game Boy Color. It also spawned Mega Man Zero, an even darker Sequel Series for the Game Boy Advance, in 2001. An anime OVA, The Day of Sigma, came with the PSP remake of the first game (Maverick Hunter X). Several manga adaptations of the first five games have added some additional characters (such as the Merloid Marti) and additional characterization for the various Mavericks and their motivations for defecting. Three Cardass card series, Rockman X: Megamissions, also got published; while not part of the official X canon, their place in the timeline falls roughly somewhere between X1 and X2 (and X2 and X3 for the third Megamissions).Zero remains the only character from the X series who appears as a playable character in the fighting installments of Capcom's Vs. series: he serves as the sole X series representative in both Tatsunoko vs. Capcom: Ultimate All-Stars and Marvel vs. Capcom 3 (his Zero incarnation also appears in SNK vs. Capcom: SVC Chaos as a Mid Boss). Both X and Zero appeared in the crossover Project X Zone, and Sigma's Mega Man X4 incarnation appears as a hidden character in Super Ultra Dead Rising 3 Arcade Remix Hyper Edition EX Plus Alpha.Do not confuse this series with Mega Man 10, the tenth game in the Classic series, which came out well after Mega Man X.Two character sheets exist for this franchise: one for the main series, and one for Command Mission.
Games in the series:
Mega Man X (SNES, MS-DOS, PC* only in Japan, Wii VC, iPhone): The series debut. The classic Mega Man gameplay has been considerably expanded upon to be far more action based, not to mention more flexible and fast.
Mega Man X3 (SNES, PS,Saturn* only in Japan and Europe PC): First game where Zero is playable. A port was released for the PlayStation and Sega Saturn, including CD-quality music, a save feature and anime cut-scenes, but only in Japan prior to its PC port and its inclusion in Mega Man X Collection. Like X2, it also used a microchip in the SNES version for 3D effects (the PlayStation and Saturn ports just used their native 3D for the effects).
Mega Man X4 (PS, Saturn, PC): Mega Man X's official PlayStation and Saturn debut. First game where Zero is fully playable, albeit in a separate campaign to X.
"Makenai Ai ga Kitto Aru" ("We've Definitely Got a Love that Won't Lose"), "Monkey," "Moon Light" and "The Answer," "CODE CRUSH," "WILD FANG," and "Don't Wanna Be" for X4, X5, X6, X7, X8, and Maverick Hunter X respectively.
And let's not leave out "One More Time" for the CD-based versions of X3.
And X2 brings it full-circle (or rather, begins the whole trend) in "Sekai ga owaru Toki" ("Moment When the World Ends").
The appearances of the main characters were slightly altered in X8 (X's helmet, Zero's ponytail, Alia's upgrade of her chest, and the overall proportions are the most blatant examples). Word of God claims that it's to make them look more human.
In Day of Sigma OVA, Sigma launches several large missiles, think ICBM sized, at Abel City. Several of these missiles touchdown and explode, leaving massive, smoking craters. Obviously, the shock waves from the explosions should've leveled the city outright.
Flame Mammoth uses the ground pound move, also used by Guts Man and Hard Man, to violently shake the ground when he lands from a jump. Problem is, Flame Mammoth's weight is 719 lb; most cars and trucks available today are heavier than he is, and they just don't release that much energy when they fall from similar heights.
Attack of the 50-Foot Whatever: Sigma's final form in X1, the intro stage bosses of X2 and X3, Eregion and General from X4, Illumina in X6, Sigma's One-Winged Angel forms in X5, X6, and X7, and the intro stage bosses from X7 and X8, as well as a reappearance of said robot later in X8.
Awesome but Impractical: A lot of X's helmet upgrades fall under this. The SNES ones, and their Gameboy Expies, aren't much use once you memorize where they'd be useful aside from unlocking that game's respective Game Breaker. Half of the regular X5 and X6 ones reduce weapon energy usage (which Zero nor the Ultimate Armor really need), the Shadow Armor speeds up sword attacks, and the Gaea Armor has no stated function at all. Aversions are X4 (game play is set up so weapons are still useful), X7 (attracts power ups from further away), and X8 (a weaponized form of X1's part, a quick charge, and unlimited weapon energy).
Charging up the X-Buster for normal mooks is only useful if you had one ready. Since they lack Mercy Invincibility, it's much faster to rapid fire them to death. Bosses are a different story. For that matter as well, charged up special weapons are situational at best, and not very useful for bosses most of the time.
Awesome McCoolname: The Guns N' Roses names for the Mavericks in X5. GRIZZLY SLASH! DARK DIZZY! MATTREX! Even Duff McWhalen is awesome in it's own silly way.
A lot of maverick names fall under this. Most of them have the formula of their element or gimmick followed by the name of whatever their design is based on. Sometimes this works too well, or they get a little more creative with the formula.
Background Boss: Rangda Bangda and Sigma's second forms in both X1 and X5; Giant Mechaniloid CF-0 in X2; Maoh the Giant in X3; the first encounter against Egregion in X4, Illumina in X6; Yadokari and Sigma's second form in X7; the second Crabz-Y encounter in X8.
Bad Boss: It is heavily implied that Flame Mammoth spends most of his time in his unit mocking those inferior to him in terms of strength. As an added bit of laser-guided karma, he's also the only one of the former Maverick Hunters in the first X game that defected to Sigma's side to not have any of his unit go with him, although given the setting where he is fought, he probably didn't need them anyways.
Bag of Spilling: The games tend to eschew all weapons and upgrades you've collected in the previous games, except for a select few. X, for example, keeps his dash upgrade after acquiring it in first game. Likewise, Zero started to Double Jump on his own starting from X6.
Grizzly Slash (Crescent Grizzly) from X5. Subverted when Monstrosity Equals Weakness comes into play, seeing as he's the easiest Boss in the game.
X8 featured Bamboo Pandemonium, the single largest boss in the game. Ironically, pandas aren't normally the first thing people think of when they think of ferocious ursine creatures. That said, his face is still very cute. And he can kill you with one hit of his Desperation Attack.
A subversion at the beginning of X5: You as the player are the one coming to the rescue of the one in distress (who was even in disrepair), when Sigma personally attacks them.
X8's Hard Mode: Whoever is the backup character will be captured by Vile after that Mini-Boss fight, and the main player character will have to traverse the rest of the final level alone. In an awesome Gameplay and Story Segregation aversion, Sigma traps the main player halfway during the Boss fight, and, true to the trope, the backup character will return to save his partner.
Blackout Basement: Spark Mandrill's stage in X1, especially if entered after beating Storm Eagle. In X6, some stages also qualify (where you have to use misleading lights as a guide), if the right requirements are met, and X8's "Pitch Black" stage.
X6. Which is a shame, because beneath the awful, awful writing, there's actually a reasonably serviceable story. Just how bad is the translation? See if you can try to make sense out of the below exchange:
Zero: "Shield Sheldon...Too bad about your previous life." Correction "Sorry about what happened before..." Shield Sheldon: Don't be. I was new as a bodyguard. That's all. Correction "It's not your fault. I was inexperienced and foolish at the time, unused to my job as a bodyguard. It was no excuse." Zero: "Maverick Hunters are supposed to be able to tell a Maverick from a Reploid. Our officers are not good enough... They could cost us everything." Correction "We're supposed to be able to tell a Maverick from a normal Reploid, and we failed in that duty. We failed you, and it cost you everything." Shield Sheldon: "Reploids all over the world have been needing you. I was useless as a bodyguard... And was useless to everyone else. When I accepted that fact, I accepted my fate. However, there turned out to be someone who needs me. He has given me one more chance. And therefore, I am going to fulfill my mission as a bodyguard now. I'll protect him, even if it means that I have to sacrifice my life. Come on, Zero!" Correction "Maverick Hunters have always been needed to protect Reploids. I wasn't any good as a bodyguard, couldn't even protect the people I was supposed to. Once I knew that I was useless, I knew there was no point in resisting any further. But now, there's someone that needs me, someone that I can protect. I'm going to perform the duty I failed at before, even if doing so means I'll die! Come on, Zero!"
There's also this gem in Metal Shark Player's stage (which is itself a mistranslation of Prayer). When faced with a wall of spikes:
While generally overlooked, Magma Dragoon is probably the biggest example of this trope in the franchise. To wit, he causes a civil war and very nearly The End of the World as We Know Itjust so he could fight the protagonists! Then again, he is based off Akuma.
More than a few Reploids in X5 seem more interested in fighting the protagonists than they are about doing something to help save the world. Many of them (especially Duff McWhalen and Grizzly Slash) say that they've been infected by the Virus and want to fight the heroes and die with dignity. Some, like Squid Adler, do actually give X and Zero what they need, only for the Virus to choose that moment to take over their minds and force them to fight.
Each X5 boss seems to have different reasons for fighting, and oddly enough, the reasons can change depending on which plan to stop the Colony Drop is active. And if the colony has already been destroyed/crashed, some bosses will already have been seized by the virus.
Bonus Boss: There's a Bonus Mini-Boss in the first game, guarding one of the Light capsules. The term got murky during X3 and X6.
Bonus Feature Failure: In X8, the navigators, Alia, Layer, and Palette, are unlockable as playable characters. They are basically feminine clones of X, Zero, and Axl respectively; however due to Gameplay and Story Integration, Alia cannot get X's capsule upgrades, Palette cannot copy enemies, and Layer gets a nice aversion by only being unable to use the Zero Armor. You also have to purchase all of X's, Zero's, and Axl's purchasable upgrades a second time in order to access them on Alia, Layer, and Palette. Additionally, using even one of them when running a stage will forbid you from choosing a navigator for that stage. Level Grinding the Navigators at least gives you something to do on your New Game+, and fully powering them up changes, of all things, the Capcom logo screen, which is pretty cool.
X1 is the only one to intersperse boss fights throughout Sigma's Fortress. The other games lock you in a room with 8 doors.
The PSP remake of the first game has X realize that Sigma had the bodies of the eight bosses repaired, but not the personalities, when he starts having the rematches.
Justified in X8: the Bosses in the Boss Rush are new generation Reploids copying the data of the Boss.
There's a variation in the second half of the final level: most of the enemies are now using their abilities to morph into weaker versions of the Sigma fought a level earlier, now a Disc One Final Boss.
X8 also changes up the boss rush chamber by color coding the teleporters, so you can tell where each boss is. Black = Dark Mantis, white = Avalanche Yeti, etc. There's also an optional boss in Optic Sunflower's stage where you must beat the Maverick under a time limit.
Boss Warning Siren: The series has this starting from the fourth game, just before the boss appeared on screen and has a dialogue with the player character. It was carried over to the Mega Man Zero and Mega Man ZX series as well, although in those cases it happened just before the fight begins after the boss's monologue.
What the effect the Maverick Virus seems to have on Reploids is. Their personalities are often altered and they become violent and homicidal, sometimes to the extent that they lose all sense of themselves and go insane. Most also join Sigma's forces after infection, though whether it's forced or willing depends on the Maverick.
The only one completely immune to the effects of the Virus is X, who nevertheless takes damage from it when he's infected. It doesn't stop him worrying about the possibility of going Maverick, but that's for other possible reasons. He is effectively immune from the Virus.
Zero also appears to be immune, and is actually strengthened by being "infected". To elaborate further: Zero's behavior in the X4 flashback is not caused by the virus. Zero was sealed because he contained a flaw in his cognitive program that made him violent and unwilling to obey instructions. This behavior persisted until the virus entered his body after Sigma damaged his armor. (The virus was stored in Zero's capsule, but had not entered his body yet.) The effects of the virus on Zero's body in X5's non-canon bad ending makes him calm and helps him remember his original objective, which quite different from the crazed Zero from the X4 flashback. It should be noted that Zero's data readings do not change when he's infected. It seems he truly is immune to the virus since it does not corrupt him.
It seems that Axl is immune as well, along with the other New-Gens whose copy chips have not been corrupted by Sigma's DNA.
Broken Aesop: The idea that the term "Maverick" being abused to deal with merely disobedient Reploids in X4 would be a lot more effective if Repliforce wasn't an army, and therefore disobedience from a massively powerful army answerable to the world governments that is suspected of murdering millions of people would be a legitimate concern. The only difference between a human army who did that would be using "traitor" or "renegade" in place of the word "maverick".
Calling Your Attacks: Zero with his Command Arts; bonus points for calling them mostly in their Japanese names. Especially of note would be X8, where X, Axl, and several of the bosses join in the act as well, with X always doing it in English for good measure. Magma Dragoon, an otherwise normal boss in X4, also does this with Street Fighter-based attacks.
X: "I have to work for the reconstruction of the world... I have no time to waste on you... If you show up, I'll defeat you."
A speech which actually has shades of Zero's personality to it.
Character Select Forcing: X6 was horrible about this; choosing the wrong armor set made the game very hard in the fortress. A variant also existed in X8, where most of the main stages required the X/Axl team to collect all or most of the items hidden throughout — effectively benching the most popular character in the series!
Characterization Marches On: Not applied to only one character, but the concept as whole for the series. In the beginning X was said to be special, not only for being the origin to all Reploids but for being to most humane out of the bunch, his emotions and potential for growth can be compared to that of any human; in turn other Reploids, and even Zero the other Super Prototype himself, commented on how they couldn't (or considered a waste to) feel and express themselves like X did. A few games later, this concept seems to be all but abandoned, pretty much all other Reploids and Zero are Ridiculously Human Robots, they express themselves and have distinctive personalities like any other human; X now is more of a outspoken pacifist, as opposed to someone who worries because he was the only one who could.
Shouldn't need elaboration. Also applies to the Z-saber in X3 and X6 (when used by X).
That's Type B. Giga Attacks sometimes fall into this category, as Type A.
Christmas Rushed: The most likely reason that X6 failed to reach its potential. Not only did it come out just a few months after X5, but the North American version hit the stores mere days after the Japanese version! (December 4, 2001 and November 29, 2001; respectively. We all know how that turned out...)
Climax Boss: Built up by four games' worth of storyline? Check. Very awesome boss battle theme? Check. Supposed to end the series? Check. Mega Man X vs. Zero is the right way to go. Tweak a few more things in the storyline, and it would even be more awesome. The battle was even reused for the future series: Copy-X vs. Zero (twice!) for Mega Man Zero, and Mega Man Model X vs. Mega Man Model Z in Mega Man ZX.
X, as protagonist of the series, fits combat in this way, but he wields a support weapon (long-range buster). Zero, who scouts along for support, is the one with the combat weapon (the Z-Saber).
Alia, Douglas, and Signas join in as support.
Axl is a balance between combat and support, while X starts fading almost fully into the support position.
Compilation Re-release: The Mega Man X Collection, compiling Mega Man X from X through X6 plus the unlockable Mega Man Battle & Chase on a single disc. It also features a Gallery where artwork, original sketches, and unused music can be unlocked through beating each game. Originally the collection was also intended to be updated versions of these games, but due to complications that arose from of using the idea for Maverick Hunter X as a remake of X-X6, the idea for both games was scrapped.
X5 is chock full of these. There's also a prime example in X6, where the plot is driven by the Big Badgetting infected by the The Virus from Zero's piece that he took in the crash site of the Colony Drop.
In X's bad ending in X5, he states his dream is to create a paradise where humans and Reploids peacefully coexist. The name of that paradise? Elysium.
After Gate is defeated in X6, X sees Isoc's lifeless body, which Alia says is similar to the Erasure phenomenon from Xtreme 2.
X8 contains some of these. Sigma makes a reference to Zero's virus infecting him in their first battle, and the colony virus is brought up by X.
Cool Airship: Storm Eagle had his personal airship, called the Death Rogumer. After his defeat, it crashed on Spark Mandrill's power plant, causing the power to fail.
The first game gives us a double-dose. Chill Penguin's stage, which has the mandatory Leg Capsule. There's also the fact that the aforementioned Boss is a Warmup Boss, meaning that defeating him would be a good start for the game!
It's tricky, but far from impossible in X1 to beat Storm Eagle first (without the ability to dash against his wind) so long as you know where and when to start running. The reward, Storm Tornado, rips through stages like nothing.
If preferred, X could defeat Chill Penguin or lose all his lives in Chill Penguin's stage after getting the Leg Upgrade, then go to the airport to face Storm Eagle and access the Helmet Capsule.
Disc One Final Boss: The X-Hunters, Dr. Doppler, General, Dynamo, Gate, Red, and, ironically, Sigma himself in X8, not once, but twice!! Capcom is in love with this trope.
Doppleganger Attack: From X4 onwards, there would be a boss that specializes in creating at least one copy of himself, whether or not his Boss Weapon was based on this ability.
Downer Ending: Zero's ending in X5. Though having finally defeated Sigma for good, Zero himself is mortally wounded in process, and as he dies, he sees the flashback of his evil past (of Dr. Wily), as well as the memory of his deceased girlfriend Iris, whom he could never meet again.
This isn't really the case in the first game, because the bosses were pretty easy to Buster to death. There were some exceptions, though — you were expected to toss a life or two to Launch Octopus before he would deign to be destroyed, for one.
When obtaining the Black Armor for Zero in X5; Dr. Light, of all people, was the one who gave it to Zero! And he (Light) made it just for him (Zero)?!
Light specifically states that he couldn't make a compatible armor, but he could boost Zero's power.
In the Japanese version, Light talks about releasing the power that sleeps in Zero.
In the same game (but a different capsule), Zero asks Dr. Light if the latter knew who created him (strangely enough, Zero was talking to what may just be a recording). Dr. Light claims he does not know; whether he's hiding the truth from Zero, or he genuinely doesn't know, tortured many a mind to no end.
"Unknown to X, his destiny has already been decided. To save mankind, he must destroy Zero. But only time will tell, when and why..."
— Mega Man X3's ending
"In his memory, he knows his destiny is fixed to do battle with Zero. And beyond this point, what will they see?"
— Rockman X3's ending
In X5, Squid Adler/Volt Kraken talks about how X killed Octopardo. Yes, it was a tragedy what happened to poor — wait, who's Octopardo? Turns out he's referring to Launch Octopus, using a mistransliteration of his Japanese name: Launcher Octopuld.
Most of the Mavericks (Icy Penguigo to Chill Penguin, Storm Eagleed to Storm Eagle, etc). The name of the rogue Maverick from the first, third, and eighth games got his name changed from Vava (which would be pronounced in Japanese roughly like "Boba", as in Boba Fett whose Expy he is) to Vile in the English version. (In fact, the reason they couldn't just call him "Boba" outright was because of trademark issues, so they had to spell it Vava). The name change in English resorting to "Vile" had, in turn, an effect on the following series (especially since Zero was created by Dr. Wily).
And in fact, the term "Maverick." They were called "Irregulars" in Japan, though this is probably because the noun "irregular" in English refers to non-conventional or private military forces of the type usually employed by governments (which might be a good description of the organization to which the heroes belong), something wholly unlike what the Japanese name was supposed to mean.
Dueling Player Characters: In X5, if you can save Zero from going Maverick then X and Zero get into an argument that escalates into a fight (with you playing whomever you took in to the level). If Zero goes Maverick then you have no choice and X has to destroy Zero.
Easy Level Trick: There's a section of Sigma's first fortress in X1 that's full of springs. The springs launch you toward the ceiling when you step on them, making the section rather difficult, but if you just use the dash feature you bounce from spring to spring avoiding enemies and zooming past the lasers, landing at the end without a scratch.
In most of the games where he's playable (both in this series and Mega Man Zero), one of the skills Zero learns is a rising slash. In X8, he instead gets a spinning rising slash, similar to Link's Spin Attack in Super Smash Bros..
He has the spinning slash since X4, after you beat Split Mushroom. It has been one of his staple techniques through this and the Zero series.
Expy: Avalanche Yeti (and to a lesser extent Frost Walrus) seems specifically based on Frost Man. Several Mavericks borrow from earlier Robot Masters, in fact: Ride Boarski is like Turbo Man and may have partially inspired Nitro Man, Dark Necrobat looks quite a bit like Shade Man, Commander Yanmark looks almost exactly like Gyro Man, Magna Centipede borrows from Shadow Man, Launch Octopus is based on Napalm Man right down to the missile launcher shoulders, Boomer Kuwanger is a mixture of Cut Man and Quick Man, and Flame Hyenard borrows from Burner Man.
X6. It gets particularly egregious in Metal Shark Player's stage, where there's a ceiling trying to crush you, instant death spikes, and ice — in a trash compactor, making no logical sense — all on the same screen.
Gate's fortress is even worse. Three words. Spikes Of Doom. No, Capcom, coating virtually every surface with them does not constitute as difficulty. Ironically, this very thing makes using the Shadow Armor a Game Breaker due to its invulnerability to spikes.
Gate's fortress also has points that are impossible to get through without certain armors/upgrades. And you can't exit the level manually. Hope you didn't have a lot of lives on hand.
If a reploid holding a part (say, the Jumper, practically essential for reaching higher-up areas) is killed, they're Lost Forever. This makes getting certain items, such as a Sub-Tank, literally impossible without restarting the game from scratch.
Fake Longevity: The Central Museum in X6, if you're trying to save all the Reploids. It requires multiple runs to get into all the rooms, each of which has at least one Reploid.
Not to mention Zero vs. Iris from X4. It doesn't end well.
Finishing Move: For X8, there's the tag-team attack, which, if inflicted as the final blow for the boss, nets the highest rank. In the latter, in a Matrix Raining Code background, regardless of the weapon equipped on the characters, they will always use the following: X has a Wave Motion Gun, Zero's Laser Bladegrows BIG, and Axl combines Trigger Happy, Guns Akimbo, andBeam Spam. If used on a boss to deal the finishing blow, the color of the field will be orange instead of the normal green, and the background static will buzz intensely.
X: Flame Mammoth (fire), Chill Penguin (ice), and Spark Mandrill (lightning). Interestingly enough, Fire beats Ice which beats Lightning, compatible with the Mega Man 6 pattern and completely opposite of what happened in the original Mega Man 1.
For X, Zero and Sigma, as the series progresses. Especially because Executive Meddling forced the series to go beyond the creator's planned ending, X5.
Even the term "Maverick" isn't safe; originally used to describe out-of-control reploids (mostly viral infected, though the viral infection wasn't realized until the third game), then it became a warped political tool to refer to any designated threat becoming a target, starting with the Repliforce (though the Repliforce's complete idiocy in handling the situation that got them declared Maverick in the first place would have necessitated their disbanding anyway). Eventually the "Maverick" label escalated to the point it became a convenient tool to refer to anyone that "needed" disposing of, even harmless Reploids trying to stay alive during an energy crisis like in the Zero series.
Four Is Death: X4 was the first game in the X series to escalate the body count up to a horrific extreme- and first to present a legitimate threat to destroy the entire planet. It was also the same installment where Zero suffered a tragic loss... the death of his crush, Iris. In addition, three more key-to-the-plot Reploids perish: Colonel, a martyr to his own cause, Double, who reveals himself as a Double Agent and gets a Karmic Death, and General, who performs a Heroic Sacrifice. That makes four major deaths in the story. note Sigma died too, of course, but he was brought back in the next game.
The calm, fatherly Signas (leukine), the fast-action Anti-Hero Zero (choleric), the conscientious defender X (melancholic), the flamboyant Axl (sanguine), Alia (choleric/melancholic), Palette (phlegmatic), and Layer (phlegmatic/sanguine).
Among the villains: Sigma is leukine; Vile has nothing but choleric faults (and dang!!); Dynamo is sanguine; and Lumine is melancholic.
Frame-Up: Happens in X4 to the Repliforce, by Magma Dragoon and his forces wearing the Repliforce sigil.
Franchise Zombie: Series creator Keiji Inafune wanted to stop the series after X5, but Executive Meddling forced three more games out of the series, and quality suffered as a result.
Freeze-Frame Bonus: During the X vs. Zero battle in X5, the winning combatant remarks that they didn't expect the loser to use Soul Body as a final attack and then collapses from their injuries. If you squint, you'll see X/Zero actually send out Soul Body to attack the player right at the end of the usual explosion that signifies a defeated boss.
Being infected by The Virus in X5 causes X to constantly take damage for a time. Zero becomes invulnerable.
This is given further backing in the battle with Maverick Zero, who, if not defeated in a certain amount of time, becomes invincible and starts spamming Genmurei.
Convoluted example in the same game: At the start, the player has to choose which character to use for the first level: either X or Zero. Choosing one will have a bonus in that character's abilities (the Force/Fourth Armor or the Z-buster, respectively). The other bonus will not be available for the rest of the game, on account of being severely damaged by Sigma prior to the first Boss battle.
And again in X5: fail to stop the Colony Drop, and Zero will "awaken." and will be unavailable for the rest of the game.
Mega Man X: Command Mission. It takes a break from the action-platforming gameplay the series is known for and delves into the JRPG scene.
Mega Man X7 forces shifts between 2D platformer and 3D third-person shooter gameplay throughout the game, with questionable results.
Grand Finale: X5. Callbacks to the earlier series and the rest of the X series, a Climax Boss foreshadowed by all four of the previous games, the return of a classic villain, and a potentially apocalyptic plot. A fitting end to the series...Too bad they had to keep making more games.
The original Japanese names of the Mavericks. X6 and beyond used these for all translations, leading to such oddities as Metal Shark Player (?), Vanishing Gungaroo, and Tornado Tonion.
"Tonion" is an attempted Woolseyism on "Debunion" (debu/"fat" and onion). Vanishing Gungaroo's name is a portmanteau of "gun" and "kangaroo." In general, many Mavericks' Japanese names are a corruption of the English name for whatever animal they resemble — Wheel Gator's Japanese name is Wheel Alligates, for instance. It's just that in X6, they stopped changing them to make sense for the English version.
Metal Shark Player's bizarre name comes from a mistranslation of "Prayer," as in praying. Suitably, he has an ability to resurrect old bosses using the scrap metal nearby.
In one case, Magna Centipede, this was actually sort of averted. It was thought that Japanese kids wouldn't know the English word "centipede", so the developers spent a lot of time trying to think of a better name before settling on "Hyakulegger," "hyaku" meaning "a hundred."
And in the cases of Boomer Kuwanger and Infinity Mijinion, the names are only partially in English — leaving English speakers baffled as to what a "Kuwanger" is.* For the record, "Kuwanger" comes from "kuwagata" (stag beetle) and "Mijinion" comes from "mijinko" (daphnia).
Gravity Screw: Cyber Peacock's stage in X4, Dark Dizzy's stage in X5, and Gravity Antonion's stage in X8.
Green Thumb: Axle the Red from X5 and Bamboo Pandamonium from X8.
Grey and Gray Morality: As the series went on, the lines separating who's the good guys and the baddies became increasingly blurred. X4 showed how the label of "Maverick" can be tossed around indiscriminately and how this can have tragic consequences, X6's plot only happened because Gate was betrayed and cast out of a society simply because he took risks no one else would (aside from his creations being too strong), and Lumine in X8genuinely believed that his force-evolution plot would end the wars.
A minor, yet mandatory, example in X6: High Max (as the second fortress Boss) requires a certain combination of attacks to beat.
The Hadouken upgrade in the original, and most of the special unlockable powers in the following installments.
An optional version is the method for unlocking Axl's special armor in X8 (you have to deal the final blow to the boss with him as well as pick up all of his upgrades), but you might well end up doing it without even knowing it.
The power weakness order can be a Guide Dang It, especially to the uninitiated. Each boss is weak to a certain power, but there is hardly any hint as to what power. If you've played previous installments, there's a bit of logic to it — wind blows out fire, fire tends to burn plants or melt ice, etc. — but you're otherwise playing a guessing game. Moreover, the game usually has a preset pattern which allows you to defeat every boss with the least amount of trouble, not to mention taking advantage of the weaknesses of any of the special bosses along the way. Again, there's not a hint on what this is. The games do tend to lean towards Monstrosity Equals Weakness, but this isn't a universal truth.
The special bosses are even worse about this. While regular bosses have an obvious reaction to the power they're weak against, most special bosses don't, so the only way to tell if you're doing it right is to check the amount of damage you do. This is particularly important in X3, as defeating the special bosses with the right weapon is essential to getting the Z-Saber upgrade for X.
The some of the Rare Metals in X8 that needs to be unearthed by a charged Crystal Wall.
Hard Levels, Easy Bosses: Most of X6. The exception is the second fortress stage, where High Max and Gate are just as hard as the stage itself.
Honor Before Reason: Maverick Hunter X has the pre-fight dialogue with several of the Mavericks point out that they're followers of this logic. X specifically points out that their actions will have them classified as Mavericks, and they don't deny it, but believe that what they're fighting for is right. The one exception is Storm Eagle, who doesn't deny the Maverick classification, but seems genuinely remorseful about the fact that he'll be considered a psycho and have to fight X as a result.
Human Popsicle: Many Mavericks weak to ice based attacks (and our heroes) will get frozen this way. Overdrive Ostrich in X2 is a variant, instead vulnerable to being sealed in crystal, but it's the same idea.
Of the setting itself. Just how well do humans and reploids get along? It'd be nice to know, but the one recurring human has been retconned out of the series recently. Becomes fairly ridiculous when Lumine mentions that said relationship has irrevocably changed and manages to confound the heroes. Do they know either?
Also, given how much personality the Robot Masters had in the Mega Man (Classic) series in games where they had dialog as well as the various mangas and adaptations, what makes Reploids so different aside from overall power?
Magma Dragoon from X4, definitely. He's one of the few "standard 8" bosses who has a larger connection with the story, and he's the only one who actually talks to you after getting defeated. Oh, and his appearance and moveset are definitely based off Akuma...
Egregion, the opening stage boss in X4, is a gigantic dragon Mechaniloid.
In-Series Nickname: Rarely is X referred to by his full title of Mega Man X (one of the few exceptions is Sigma during X1's endgame).
Judge, Jury, and Executioner / Knight Templar: The Maverick Hunters were forced into this trope more often than not due to both extreme circumstances and the complete unwillingness of their targets to cooperate. Needless to say, X was very unhappy about this fact.
Kangaroo Pouch Ride: He starts the battle riding a mother kangaroo-shaped battle mech, its cockpit being in its "pouch".
Suddenly Reploids, thanks to their advanced programming that allows them to enjoy a personality, can malfunction and end up wanting to exterminate and not care about humans, aptly named Mavericks. Thanks to the circuit that makes X "worry" about the value of humans and reploids not being perfect in other reploids, and thus extremely vunerable to the virus, which exploits the cracks.
This is also at times implied to be an inherent part of the reploid's free will: Just as a human can freely choose the Dark Side, reploids can do the same. The flaw simply makes them more vulnerable to physical and external influences on their behavior.
King of Beasts: Slash Beast from X4, who has a leadership position in charge of an army unit.
Land, Sea, Sky: In X4, you face off against high-ranking officers of Repliforce's Army (Slash Beast), Navy (Jet Stingray) and Air Force (Storm Owl)
Levels Take Flight: The stages for Storm Eagle (X1), Storm Owl (X4), The Skiver/Spiral Pegacion (X5), and Wind Crowrang (X7) all involve (in some way) their personal armadas, with the actual battle against these Mavericks usually taking place on their personal aircraft/flagship.
Limit Break: Giga Attacks. Also, each boss, starting with the third game, will unleash a more powerful attack starting at 50% health, but only once (it either is very difficult to avoid, or has a lingering effect).
Live Item: Technically, the Reploids you need to rescue in X5, X6 and X7. They'll give you goods (commonly a 1-Up) when you rescue them. The X6 and X7 variants give you equipment as well.
Locked Out of the Fight: In X2 and X3 notably, Zero will arrive in the last level, declare he is "Going ahead to destroy the core," and will "catch up to you later." Also mentioned in the X5 intro stage and after the final battle.
Lost Forever: In X6, there are Reploids scattered throughout the levels waiting around to be rescued. God help you if a nightmare virus infects one of them, because they will be lost forever, taking the items they give with them.
X5 and the cannon. The cannon will only successfully fire half the time, no matter how well you do.
Also, the shuttle can in fact fail to destroy the colony even if you do gather all the parts. Conversely, you can fire the cannon right off the bat and it actually has a decent chance of destroying the colony.
The success of the shuttle seems tied to which character you've been giving preference to. For instance, a playthrough focused on building up Zero will usually have a successful Shuttle Operation, for obvious reasons.
Macabre Moth Motif: Morph Moth, whose stage is the robot equivalent of a graveyard with zombies.
Meaningless Lives: X5 and X6 were especially ridiculous, as getting a Game Over did not even make you lose your level checkpoint. Also, the littering of hostages in many stages, each of whom granted an extra life, meant maxing out at nine lives was too easy.
Mechanical Evolution: Done rather uniquely; all Reploids are 'replica androids' derived from the titular X, who was designed with 'limitless potential,' the capability to evolve to (hopefully) overcome any obstacle he was presented with. As X is forced to fight and evolve, more and more powerful Reploids can be made based on him, allowing the species itself to evolve over time.
Minecart Madness: Armored Armadillo's stage in X1. The minecarts themselves travel very fast, mow down nearby Mooks in an instant, and are in fact required to cross the large chasm connecting the end of the mine to the entrance of the Boss Room.
Mini-Mecha: The Ride Armors seen in most of the games, available for use to the playable characters. Vile more than often uses them in his appearances as well.
Moral Dissonance: Arguably, much of the series centers around this, given what Maverick Hunters actually do. This issue is occasionally addressed, albeit very mildly, and nothing ever changes regardless. However, it does lead into the Zero series...
Multiple Endings: Subversion in X2 and X3. Gathering all of Zero's parts and keeping the same character alive, respectively, definitely changes things in the final battles, but they only slightly affect the ending. Played straight in later games, though.
Multi-Platform: Mega Man X Collection and Mega Man X: Command Mission, both available on PlayStation 2 and GameCube.
Multipurpose Tongue: Sting Chameleon from X1 is all about this trope. He uses his tongue as his primary attack, and can hang from the ceiling to rain damaging spikes down from the ceiling.
Mutually Exclusive Powerups: In X3, in addition to the Powered Armor, you can get an upgrade chip from the capsule that will upgrade one of the parts. Once you select one (by accepting Dr. Light's offer to add the chip to the respective part), you can't have the others, but you can still get the other armor parts. However, there's a secret way to get all of them at once, and with a nice touch of gold color!
New Game+: Xtreme 1 and Xtreme 2 allowed this, particularly with the latter's parts system. X7 also featured this so you can carry over the upgrades you got from Reploids. X8, which features the most item collection in the series, lets you cut loose with all your prizes — indeed, it's the only way to unlock each character's special armor.
Combined with every other instant-kill trap, utilized in the most sadistic way possible.
No Cutscene Inventory Inertia: Any animated cutscene with X shows him in his base form, with whatever armor powerups you have being absent. In-game scenes keep the armor on though, leading to continuity problems in X7 and X8 which go from in game to animated during the final boss fights.
Odd Names Out: The Maverick bosses follow the "Adjective, then Animal-Noun" naming convention except the English version of X5, whose Mavericks were instead named after members of Guns N' Roses. Also, X6 is the series starts going with the original Japanese names of the Mavericks, leading to weird names like Infinity Mijinion and Rainy Turtloid.
In X7, Zero comes close to literally being one, after X retires, until at least he was joined by the "volunteer" Axl.
In fact, most of the legwork of the Maverick Hunters seem to rely only on X, Zero, and (later) Axl. It's only in The MovieDay of Sigma that other Maverick Hunters are actually shown fighting (and, even then, just briefly).
This is played with, since the Mavericks always seem to rely on a mere 8 bosses, suggesting that both sides deploy forces against each other beyond what we see.
Outside-the-Box Tactic: While many bosses have Logical Weaknesses, Launch Octopus has one of these - the boomerang attack can cut off his tentacles and prevent him from using his homing and energy drain attacks. Use the same attack on Flame Mammoth to cut off his trunk and stop him from shooting globs of oil he can turn into pillars of fire with his main weapon.
Day of Sigma, available after finishing the first game's remake. It's a prequel to events in the series; however, it retcons certain aspects of the series canon (eg. Sigma's motivations, Dr. Cain's death [he was shown/mentioned in games up to X4; especially in X2, where it was he who rebuilt Zero from the parts X stole from the X-Hunters], etc.).
It should be noted that Maverick Hunter X was intended to use Inafune's originally intended plot for the X series, so maybe Dr. Cain wasn't supposed to be around for that long.
Pandaing to the Audience: Bamboo Pandamonium from X8. He's far from cute and cuddly though, being able to do heavy damage with his attacks.
Platform Battle: A few bosses, most notably the rematch against Serges in X2 (set on floating platforms above a bed of lethal spikes) as well as Gate's boss fight in X6, this time above Bottomless Pits.
Player Guided Missile: In X2, the Magnet Mine can be steered vertically while it's in flight, both in normal and charged forms. In X5, the Flash Laser is fully steerable at the cost of not being able to move X while it's in use.
Many Reploids have these. In particular, most of the humanoid ones have at least one on their forehead.
This is pretty much a trademark symbol of Gate's Reploids in X6.
Power Levels: In X3, the images were combined with ratings for strength and speed. Most of the bosses topped at about 10,000 for one or the other, Sigma made it up to 16,000 both, and Battle Body Sigma reached 25,600 for both (despite the fact that he was slower than dirt). Interestingly, X and Zero both had ratings of "?", which is confirmed in X4 when Cyber Peacock proclaims that X's potential is limitless (though he immediately tries to discredit his readings by claiming it's not possible).
Pre-Explosion Glow: Starting from X4 onwards, all of the bosses does this after being defeated (sans Dynamo, who isn't dead).
In X5, Livesaver had growing concern of Zero's immunity to a virus he carries. Depending on how the story unfolds, turns out said virus releases Zero's evil side.
In X6, the Inspectors are labeled Mavericks on a whim. The Inspectors turned out to actually be willingly working for someone evil.
Somewhat of a Double Subversion regarding their backstory: Gate (the Inspectors' creator) wasn't evil back then, but his creations ended up branded Maverick or otherwise killed off because of the other scientists' jealousy at his talent (and some of his creations are indeed dangerous, but not malicious). It drove Gate bitter and evil, making people's suspicions right from a certain perspective.
From the end of X3: "To save mankind, Mega Man X must destroy Zero." A straight example in X5: Zero and X indeed fight, but X wasn't able to destroy Zero (although he did die, by Sigma's hands), because they were the best of friends. The same prophecy was then averted much later, in the Zero series. According to Inafune, X is originally the Big Bad of the first game, a Knight Templar exterminating Reploids for the sake of humanity, and Zero The Hero trying to save the remaining Reploids because they were wrongly accused of being "Mavericks". It was only because of Executive Meddling on the X series, that the true, "twisted" events of the prophecy never came to pass, replacing X with a clone.
Of course, the wording used is different in the Japanese version (see "Dub-Induced Plot Hole" above). In this case, true to the prophecy, in X5, he had a battle with Zero, for reasons differing depending on which path you took, thus averting this trope.
Psycho Electric Eel: As an exception to the "no other electric fish" rule, Volt Catfish from the third game.
Rank Inflation: X5 goes for B, A, SA, GA, PA, MH, and if you're lucky, MMH or MEH ranking scales. X6 goes D, C, B, A, SA, GA, PA, and UH, although in X6's case, your rank as based on how many Nightmare Souls you gathered rather than your actual performance in the stages. X7 does the same as X6 but goes back to being performance-based. X8 goes D, C, B, A, AA, and AAA (or S in the Japanese version).
Real Time Weapon Change: Since the series started on the SNES, the shoulder buttons were used as an alternative to pausing for the weapons.
Duff McWhalen's stage music is Bubble Crab's stage music remade for the PS.
The battles against the Black Devil and Ragna Bagda in X5 are set to remixes of their their boss themes from 1 and X1 respectively.
Gate's stages from X6 use a sped-up remix of the second X-Hunter stage from X2.
Removable Shell: Armored Armadillo of X1; he'll lose his shielding if he's hit with the Spark Shot.
Crystal Snail from X2. If you hit him with the Magnet Mine, his shell flies off, causing him to lose his only method of defense and causing him to focus on trying to reclaim it over attacking you... which you can prolong indefinitely by knocking the shell around.
X8 has Earthrock Trilobyte, who, like Crystal Snail, also has a shell that flies off by guard-breaking attacks, removing his only protection against the Hunters' attack and he'll try to reclaim it. It can also be destroyed outright hitting him with Gravity Antonion's weapon, rendering him completely vulnerable.
Road Runner PC: For this series (as well as Zero and ZX), the greatest advantage a player has over most enemies (including many bosses) is in the player's vastly superior speed and or agility. And you will need it.
Rouge Angles of Satin: From the first game: "YOU GET HORMING TORPEDO". They didn't bother correcting it in the US version, it seems. PAL version seems to have fixed it, though.
Schrödinger's Player Character: In X4, you can choose to play as either X or Zero, and when you choose one, the other won't appear in the storyline (save for Zero appearing once in X's ending). Subverted in X5 when choosing the playable character only means keeping different power-ups (Z-Buster for Zero, nerfed Fourth Armor for X); both characters still appear in the story proper, and you can play as either one freely by the next levels.
Secret A.I. Moves: X5 is pretty bad about this. When you end up challenging either X or Zero, the character gets moves you cannot (or no longer can) use. X can use several powers from the previous game, which he can use a lot better than he ever could in that game, while Zero gets a huge upgrade to his ranged attack abilities. The latter might have been excusable if only Maverick Zero could do it (instead he he's just cheaper and gets a one-hit kill attack on top), but Zero can use these powers regardless of the circumstance.
In X3, there's a secret level that can only be accessed through specific teleportation capsules, that take you to an abandoned factory where you can fight Vile, The Dragon of the first game. Finding and beating him will result in another boss appearing in his stead later on, where he would normally find and attack you.
Then, in X6, there 's a secret "Nightmare Stage" for every normal level, where you can find secret upgrades and bosses.
Seldom Seen Species: Some of the Mavericks fall under this. Some players may not be aware that Infinity Mijinion is based on a water flea, and he makes some hypocritical remarks about Mavericks being useless fleas.
YouTube Let's Player HideofBeast takes this to downright masochistic levels, having done a minimalist, no damage speed run of X4-6 on Extreme Mode. This is especially painful when you take into account the horrid level design of X6 and how much of a pain in the ass it is just to beat it normally.
X8 ends with one, where Lumine, in his last breath, knocks Axl comatose, and leaves a strange fragment on his helmet. It gets no mention in Command Mission, which might or might not be the next chronological game.
Earlier, in X1, after the end credits: Sigma shows up on a screen and taunts X, saying that his spirit still lives on, which turned out to be a hint about Sigma's true nature as The Virus.
Shades of Conflict: The games can vary tremendously. In the first through third games, you are heroically trying to put down a murderous revolution mostly caused by an army of infected replies. In the fourth game, you're a bit more trigger happy, dealing with wrongfully accused people doing everything in their power to justify your need to take them down. The games just get more ambiguous from there.
Shared Life Meter: Rangda Bangda (which also reappears in X5), a giant robotic face that's defeated by destroying both it's eyes and its floating robotic "nose".
Shock and Awe: Spark Mandrill, Volt Catfish, Web Spider, Squid Adler, Tornado Tonion, Gigavolt Man-O'-War.
There are hidden special attacks for X in the first two games that mimic Ryu and Ken's signature attacks from Street Fighter. X's Shoryuken returns in X4 (charged Rising Fire) and X8 (comes with the Ultimate Armor).
Magma Dragoon is an utterly blatant Shotoclone, complete with Akuma's topknot and magatama.
In X8 as well, two of Zero's techniques change into the Shoryuken and the Tatsumaki Senpukyaku when he's equipped with the K Knuckle. X can use the Shoryuken as well if he's equipped with his Ultimate Armor.
Possible pun here, but the series is known for having little Mining robots known as Metools. In the X Universe all of the robots have been made obsolete by the creation of Reploids which would make this series equivalent Mettdroids
Two of the final stages in X5 are based on respectively, Quick Man's stage and the first stage of Sigma's Fortress from the first X game... containing updated versions of the Yellow Devil and Rangda Bangda, respectively.
To Blade Runner with the "retirement" of Reploids, and Reploid being short for Replicant Android.
Also, someone at Capcom is a Guns N' Roses fan. Aside from the English names of X5's bosses, check out the background in X5's jungle stage.
Also, in X6, after you defeat a boss, an orb drops down, and when you touch it, victory music plays and the level is complete, which could be seen as an homage either to the first Mega Man 1 or Castlevania.
In X5, you can skip the eight Maverick stages by immediately using the Enigma Cannon and/or the Shuttle, and then you can access the fortress stages. Amusingly enough, you can take out the space colony with just the Enigma Cannon right off the bat if you're lucky, which doesn't happen if you do things the "normal" way.
Likewise, the three X Hunters from X2 move randomly from stage to stage, and appear only in designated rooms within the stages, sometimes off the stage's main path. There is also an additional boss in the final stage, depending on whether or not you defeated all three X-Hunters while battling the eight Mavericks.
Vile's reappearance in X3 is completely optional, depending on whether or not the player finished that stage before he appeared on the map.
In X6, if you beat Nightmare Zero and High Max in the secret areas, Gate's secret lab becomes accessible.
X3: Blizzard Buffalo's ice prison and Crush Crawfish's Spam Attack
X4: Web Spider's webs and the yellow orbs in Cyber Peacock's level.
Soundtrack Dissonance: Blaze Heatnix's level. His stage music is one of the fastest paced and intense songs in the series. The level itself, on the other hand, is one of the slowest paced in the series, comprised almost entirely of battles against the same mini boss.
Mega Man X8: Paradise Lost. Guess what's the final boss' attack name?
In Maverick Hunter X, after Zero sacrificed himself to destroy Vile's mech:
X: "Zero! Hang in there, buddy!" Zero: X... I'm always telling you... to be more careful... but now look at me... X: "Don't waste your energy talking, Zero. We've gotta fix you up." Zero: "There's... no time for that... Sigma is close... Very close..." X: "Zero..." Zero: "Go now... Maverick Hunter X..."
Storm Eagle also calls X by his full title, but only on the second playthrough.
Too Long; Didn't Dub: In particular, the X6 bosses' name keep their original Japanese names, as opposed to the bosses of the past (e.g X4 Cyber Kujacker into Cyber Peacock).
Tragic Monster: Some Maverick Bosses are actually innocent individuals (e.g. Blizzard Buffalo), or have sympathetic backstories (e.g. most X6 Investigators) before being infected; and then there are other Mavericks who are only termed as such by the government (most of the Bosses in X4 (though granted, their army was acting treasonously) as well as Command Mission's Rebellion army). The most tragic one of all, is, of course, Zero's girlfriend Iris.
Trippy Finale Syndrome: X5, to the max. It is caused by the concentration of the Zero virus being so strong that it caused the formation of a "Zero Space", in which Cyberspace and the ordinary world merge. This is similar to Omega's power causing doors to Cyberspace to appear in Zero 3. He is, after all, the original Zero.
In contrast to the NES originals, bosses start becoming more dangerous when low on HP. In X1, this was limited to two of the Sigma fortress bosses simply moving faster, but in X2, the Mavericks began unleashing new and more powerful attacks after their HP hits 50%.
In X2, Morph Moth starts the battle in a larval stage and doesn't reveal his true form until low on HP. Meanwhile, Flame Stag doesn't reveal much in the way of new attacks, but the color of his fire upgrades from red to blue (in the rematch against him, he already starts out blue).
Unblockable Attack: In X8, X's fully charged buster shot, Zero's 3-hit sword combo, and Axl's rapid-fire shots (to be exact, every 8th shot) can flip Metools over. They all also have at least one boss weapon that breaks shields like the previously-mentioned techniques, and one that bypasses shields completely.
X3 got a PlayStation/Saturn re-release with a revamped soundtrack and a full video opening and unique openings for each Maverick. It was only released outside Japan on PC until the release of Mega Man X Collection, as it was the version of X3 included.
Said X Collection was supposed to be one, but Capcom Japan forced the developers to release the games in their original state so as not to upstage the Maverick Hunter X series. This move backfired in the long run, as the demise of the Maverick Hunter X series meant that no one would ever get to experience any updates to the series, old or otherwise.
Unique Enemy: The Mega Man (Classic)-era Bubble Bat in Armored Armadillo's stage, which drops an extra life 90% of the time you kill it. Relatively easy to miss, as you're supposed to be on a speeding trolley when you go past him.
In X6, Capcom actually included a way to get Zero's Black Armor without the use of a cheat code. However, a design oversight made it impossible to achieve. What did you have to do? Defeat Nightmare Zero when he's at level 4, which you get him at by obtaining 5,000 Nightmare souls. Problem is, getting 3,000 unlocks Gate's Lab, which removes the Nightmare Zero fight entirely and replaces him with Dynamo. Oops!
It's seemingly impossible to beat Gate's Lab 2 with Unarmored X or Shadow Armor X due to an air dash-only jump, but you can clear it with either clever use of Blaze Heatnix's weapon (swing the fire blade repeatedly in the air to float over the gap), or by combining BOTH the Hyper Dash and Jumper parts, and then dash jumping off the wall at the absolute lowest possible spot.
Shades of this appear in later games; the Maverick Hunters dutifully destroy any Reploid that goes "Maverick", according to their standards...which would be fine, if those standards were limited to those Reploids actively infected with The Virus or deliberately causing grievous harm to humanity and/or Reploidkind. Unfortunately, it seems to encompass any form of resistance against the natural order of things, including otherwise non-hostile acts like peacefully exiling themselves to their own space colony (Repliforce and the Rebellion Army; though there are reasons for both of those, albeit not entirely concrete justifications) or merely having traits that could potentially cause problems with controlling them (Nightmare Investigators). In fact, it's revealed in X5 that the (unseen) Maverick Hunter commander in charge during X4 retired in disgrace for misapplying the label of "Maverick" on Repliforce, and thus causing the deaths of hundreds or thousands of relatively innocent Reploids. Furthermore, the commander who labels the Rebellion "Maverick" in Command Mission was a Manipulative Bastard who fancied himself a god.
While Repliforce and Nightmare Investigators are both sympathetic in one way or another (Repliforce was are framed, and some of its members are actually moles working under Sigma, and it's Magma Dragoon who brought down the Sky Lagoon; the Nightmare Investigators were accused as Mavericks because they're hard to handle and their DNA datas are unreadable, for pretty petty reasons), they do have their own faults (Repliforce refused to resign in for interrogation and instead they go to their Kill Sat and they want peace and seclusion out of Earth, it's just that they're breaking the law, and let Jet Stingray destroy a city to serve as a distraction for their exile; in the Nightmare Investigator's case, the Hunters saw through the ruse created by the Investigatrs the moment Isoc started calling for Reploids to volunteer to help destroy a "ghost" of Zero gone bad, and said "ghost" are actually Gate's own creation).
That's also forgetting a crucial detail: They try to reason with them first. In every case, barring purely evil Mavericks like Split Mushroom, and the ones that are completely out of their minds like Dark Dizzy, X and Zero give everyone they encounter a chance to cooperate or surrender depending on the situation. In X4, the Repliforce soldiers are asked to peacefully surrender. They refuse, and try to kill X or Zero. In X5, the Reploids with parts for The Enigma/Shuttle are asked to cooperate, the only one who cooperates without a fight is Squid Adler, who goes insane from the Sigma Virus immediately afterwards. In X6, all the investigators are reasoned with first but even the sympathetic ones like Rainy Turtloid choose to obey Gate rather than help the Hunters. Turtloid's case is particularly sad. While he says he understands where X/Zero is coming from, he just can't bring himself to betray the one who gave him a second chance, which is at least understandable given that Gate was punished for protecting him back when he was alive.(All the investigators were resurrected Reploids that Gate had originally created.) and X, for his part, is horrified at the thought of fighting him.
Victory Pose: All of the heroes has one each after defeating a boss.
All of the villains in this series (and also ZX series) are called Mavericks, ranging from the virus-infected ones, wrongly-accused ones or just the plain criminals with free will.
Mega Man Zero plays this from the different side, as La Résistance who is composed of innocent Reploids are judged Mavericks just because of energy shortage.
The Virus: The Maverick Virus; not counting an Early-Bird Cameo as the Final Boss in X2, its role becomes prominent in the series from X3 onwards. There are other variations, like the Nightmare Virus in X6 and of course the Sigma Virus. X8 gives us Sigma's very DNA, allegedly encrypted into all the data of the New Generation Reploids.
Wall Jump: This game is the king of this trope. Combined with Jump Physics, the players can climb a single wall with this. This is later carried over to Zero and ZX series.
Played with in X6; as the second part of the Infinity Mijinion level opens, you do have to go right to progress. But directly to the left of the starting point (Behind the Black) is one of the game's upgrade capsules, which most players would miss because of this trope.
There's also some variations in other games: The heart tank for Storm Eagle's level is directly above the player, unreachable from the start point, so you have to go right, then left when you get high enough. In Armored Armadillo's stage, you need to go right to get away from a death machine, then go back left to get a sub tank. In fact, from the very first game, the X series has delighted in hiding things from the player that assumes forward is right.
The general case applies as well, starting from the original Mega Man (Classic) days and carrying forward from there; most levels (if not all) start you at the left end and send you to the right.
A subversion: in X2, Sigma is fought in one of the 8 initial Maverick stages (the Central Computer), which is not necessarily the first one to be played. Plus, the map shows that the fortress where all the "Final Stages" were is in ruins, but trying to go there will still take you to the Central Computer stage. Most Western players did this anyway, because the translation left out Sigma's line "I'll be waiting for you at the Central Computer..."
Subtly implied in X5 when X or Zero goes to fight Sigma. In the background of the first fight are two dilapidated capsules, one red and one blue...
You Can't Fight Fate: No matter what happens in X5, Zero and Mega Man X will always have their destined battle. This was already hinted at since X3.
You Can't Thwart Stage One: In X5, your initial defeat of Sigma is part of his plan, setting in motion a Colony Drop. You then spend most of the game building machines to prevent the crash — but no matter how good your luck is, you can't stop it completely. What's more, the second thing you try may turn Zero evil, and this was also part of Sigma's plan. (Even if Zero's okay, he and X will end up fighting, leaving just one hero to stop Sigma.)
Zee Rust: The first game's pre-title intro is done as a computer read-out on X's data and Dr. Light's warning about his abilities, prefaced by a boot-up sequence. Despite the OS being as advanced as 2114 (with RAM to match: all told, the system's packing 40,960 terabytes of memory) asides from the blue typeface it's a clear knockoff of DOS.