History HeWhoFightsMonsters / VideoGames

** The entire storyline of ''DAII'' is built on this. [[spoiler:The leaders of both factions eventually give in to their demons. Knight-Commander Meredith, who had fought blood mages all her life (okay, and an ArtifactOfDoom), calls for the Rite of Annulment ordering the death of every mage in the city for the action of one rogue mage; and First Enchanter Orsino, who resorts to BloodMagic to put down Meredith and the templars who had oppressed them. They both [[JumpingOffTheSlipperySlope jump off the slippery slope]] for what they see as the [[WellIntentionedExtremist right reason]]. The major irony is that they both ignore the most important flaw in their own factions; Orsino allows a serial killer mage to go unchecked because he went so far that he broke new ground, and Meredith uses dangerous anti-magical techniques to instill absolute order -- including demonic possession and end up literally becoming monsters that are the opposite of their class; Orsino uses blood magic to become a hulking corpse bruiser with a slippery-quick center (Reaver and Assassin), and Meredith uses a cursed sword in the name of the Maker, not realizing that she just used magic to jump twenty feet in the air and re-activate the city's antipersonnel robots (Battlemage and Demon Summoner).]] It really fuels the game's relentless GreyAndGrayMorality.

** ''VideoGame/FarCry4'': All the major cast members start off trying to do some things moral and right, only to become just as cold-blooded and ruthless as the people they fight against; this includes [[spoiler:Pagan Min, as you find out during the GoldenEnding]].[[note]]DLC reveals Pagan was always AxCrazy, but he did care for Ishwari in his own way -- before ruining their relationship by continuing to obsess over killing her husband instead of protecting her.[[/note]]

** One of the potential unifying warlord states in Russia is Omsk, a fortified citadel ruled by militant ultranationalists who will stop at ''nothing'' to enact the Great Trial, their plan to [[FinalSolution utterly annihilate the German civilisation with nuclear and chemical "revenge" weapons]]. So great is their vindictive madness that not even the spectre of nuclear apocalypse will turn them away from this goal.
** Israel exists in this timeline, and one potential direction it can go is towards the cause of [[BecameTheirOwnAntithesis building a Jew supremacist ethnostate and forcibly driving out all non-Jews from the country to keep it pure]] for the true "MasterRace". Really, the real NightmareFuel that makes ''The New Order'' is how it presents the psychological and ideological consequences of a Nazi victory as well as the physical human cost: worldviews based on hatred and Darwinism become validated by the Nazis' success, [[DownerEnding and even a people as peaceful and benevolent as the Jews are corrupted and made to accept the brutal logic of their oppressors]].

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* ''VideoGame/BleedingSun'': If Yori decides to kill Ichiro out of vengeance, [[spoiler:he does so in front of the latter's son Genji, mirroring how Ichiro killed Yori's father in front of him. He also seeks to kill Genji to complete the cycle of revenge, which is exactly what Ichiro wanted to do to Yori. If he accepts the Tortured Soul's power, releases Chiyo's dark energy, and loses to his friends, he gains a SuperPoweredEvilSide similar to Ichiro's.]]
* ''VideoGame/GrandTheftAutoSanAndreas'' has DirtyCop Frank Tenpenny who uses his power to keep street gangs in check to do things a normal cop wouldn't be able to get away with, such as manipulating criminals for his own ends. As time goes on, Tenpenny starts making deals with gangs, gets in on the drug trade, and backstabs people, just like the very same people he was fighting against.
* King Kashue will quote this word for word to the Trestkon towards the end of the [=WorldCorp=] ending in ''VideoGame/TheNamelessMod.''

* Ryu from ''Franchise/StreetFighter''. In the ''[[VideoGame/StreetFighterAlpha Alpha]]'' series and beyond, this trope is a problem that he is constantly wrestling with. Ryu strives ToBeAMaster but his fighting style has an inherent dark side called the ''Satsui no Hado'' (Surge of Murderous Intent) that materializes if he should ever prioritize victory over humanity. He is in a constant struggle to balance pushing himself to new heights in battle with not becoming so consumed with winning that he will fight without honor or mercy. His nemesis, Akuma, has long-since embraced the darkness and wants Ryu to as well, only adding to his struggle.
* Raiden from ''Franchise/MortalKombat'' shows shades of this [[LateArrivalSpoiler when he is given]] a DarkReprise. He becomes a KnightTemplar that borders on an OmnicidalManiac. This is made much more explicit [[spoiler:in various ''VideoGame/MortalKombatX'' endings, where he attempts to conquer Outworld by brute force until Kotal Khan convinces the Elder Gods to put a new Mortal Kombat tournament in place; effectively reversing the role he once had when he defended Earthrealm from Shao Khan]].
* It's probably appropriate, given that they turn into monsters, that the Harmonixers of ''VideoGame/ShadowHearts'' face this. The downside to their PowerCopying is that in addition to taking in the powers of those they slay, they also take in their hatred, sorrow, and anger. This can have consequences including death, madness, and souls being twisted to evil, or becoming feral beasts that exist only to destroy.
* Prince Arthas in ''VideoGame/{{Warcraft}} III''. This was apparently engineered (or at least [[FlawExploitation taken advantage of]]) by the BigBad, to the point of sacrificing Arthas's target so that the fall could be complete.
** The box for ''Wrath of the Lich King'' even reads "If you stare long into the abyss... the abyss stares back into you."
** The ''VideoGame/{{Warcraft}}'' series uses this one a lot. The only villains in the series (including the Big Bad, Sargeras) that haven't been driven mad by endlessly fighting monsters are the [[Creator/HPLovecraft Lovecraft]]-inspired Old Gods, the demons Sargeras corrupted and forced into his [[DemonicInvaders Burning Legion]], and the Naga, who were made by the Old Gods (they did not even have a choice!).
** Clearly lampshade-hung by Malfurion regarding Maiev in ''Warcraft III'', when he says that she has become "vengeance itself" and hopes that, in her pursuit of Illidan, she will not wreak even more havoc than him. But by the end game of the ''Burning Crusade'' expansion, Maiev says that she is 'indeed nothing' after downing Illidan.
*** In the expanded universe novel "Wolfheart", Maiev returns, disgusted at the night elves having become so reliant on outsiders as well as allowing the Highborn to return to their society, and attacks Malfurion and Tyrande. Malfurion, who may have been still a tad bitter Maiev finally caught up to Illidan, lampshades this as she's fleeing when her attempt fails.
---->'''Malfurion''': "Who's the traitor now, Maiev?"
** Illidan himself qualifies after consuming demonic powers to fight the Burning Legion. After being banished by his brother, he briefly works for the Legion in bringing down the Lich King. Failing that, he retreats to Outland to escape their wrath. The evil magic he consumed, which also fills the very air of Outland, drives him mad between ''VideoGame/{{Warcraft}} III'' and ''VideoGame/WorldOfWarcraft'', and while he's still [[WellIntentionedExtremist intent on fighting the Legion with the creation of his demon hunters]], he's completely willing to go to ''any'' lengths to do it, even willing his own troops (with the exception of said demon hunters) to their deaths by the hundreds to serve his ends.
** Demon hunters themselves take this risk in pursuing their path (in lore, but not so much [[GameplayAndStorySegregation in gameplay]]).
** After the death of the Lich King, [[spoiler:Sylvanas]] seems hell-bent on becoming the leader of a new Scourge by using the displaced Val'kyr to raise the dead to repopulate the Forsaken. Even ''Garrosh'' points out how close [[spoiler:she]] is to becoming like the Lich King.
*** In Battle For Azeroth, [[spoiler:she burns the world tree filled with refugees just to make a point. According to her, this all started when she became an enemy of Hope itself.]]
** The [[KnightTemplar Scarlet Crusade]], the fanatical undead-hating organization, which has made the exact same journey as the Lich King/Arthas, have, as of Cataclysm, [[spoiler:become undead themselves, because of Balnazzar's VillainousBreakdown.]]
*** Same can be said for the renegade group of Scarlet Crusaders that Alliance players assist. They succeed in purging the Scarlet Monastery of its corrupted members but ultimately succumb to insanity after killing their own men.
** Fandral Staghelm seems to have come full circle on this. [[spoiler:During the War of the Shifting Sands, his son, Valstann, was killed in front of him by the Old God-aligned Qiraji, which he [[DespairEventHorizon never fully got over]]. He went to any length to bring his son back to life, even if it meant corrupting the night elves' world tree, Teldrassil. An Old God agent, posing as Valstann, completely shattered his illusion and the remnants of his sanity. By the time of the Cataclysm, he commands the Druids of the Flame, a breakaway sect aligned to Ragnaros the Firelord - who himself answers to the Old Gods.]]
* The opening quote of the beginning cut scene of ''VideoGame/BaldursGate''.
** And ''VideoGame/{{Diablo}}''.
*** And ''VideoGame/TooHuman'', which even gets its title from another Nietzsche work, ''Human, All Too Human''.
*** And ''Legends of Valour''.
** ''VideoGame/BaldursGate'' is actually a subversion, since, while it is certainly possible to gradually turn to evil in your war against Sarevok, the game strongly rewards you for being good. Arguably, the entire game series is an ''inversion'' of the quote: [[spoiler:as a child of the God of Murder, the abyss is constantly gazing into you, but if you remain good in spite of your heritage, the powers of the God of Murder become good-aligned instead.]]
* This trope heavily permeates [[VideoGame/TheLastOfUsPart both]] [[VideoGame/TheLastOfUsPartII games]] in ''Franchise/TheLastOfUsPartII'', video game series.
** In the first game, Joel has committed many horrific deeds both prior to and during the narrative of the games that, while he does what he does to protect and survive in a post-apocalypse, it's questionable at best if he can really be considered any better than his antagonists. But then he's hardly unique here. Even the Fireflies, regardless of whether one might side with their goal of saving the world from the infection, are ruthless.
** [[spoiler:The sequel kicks off with the consequences of the first game's final act, where he kills the Firefly physicians in order to save Ellie, and lies about it, heavily straining their relationship. Abby, [[YouKilledMyFather the daughter of]] one of those murdered physicians, engages on a RoaringRampageOfRevenge, engaging on a destructive journey to avenge her father, ambushing Joel with the help of her WLF comrades and torturing and killing her]]. Ellie, after being ForcedToWatch the murder after failing to save her, getting nearly killed by the WLF teammates, and wracked in the guilt of failing to mend of her relationship with Joel, is driven to revenge towards Abby. From this point onward though, Abby [[VengeanceFeelsEmpty feels empty and conflicted]]; she only engages in fighting Ellie when given no choice, and finds healing and redemption through [[FamilyOfChoice helping Yara and Lev escape the Seraphites.]] However, she still commits many brutal acts [[WithUsOrAgainstUs against anyone she perceives to be an opponent]]. She even nearly kills Abby's love interest, Dina, with glee, even more pleased when Ellie pleads the latter is pregnant. (Ellie was responsible for Mel's death, but unlike Abby with the Dina incident, Ellie was absolutely horrified when she realized Mel was pregnant.) In other words, she holds [[LackOfEmpathy little empathy towards Ellie]], not realizing or caring Ellie has felt a similar sorrow and rage all this time. Likewise, Ellie, now empty from her losses, sadistically hunts Abby down, going from killing [[PayEvilUntoEvil her ruthless Wolves teammates who assisted in her murder of Joel, and almost killed her in turn]] to threatening if not killing Abby's absolute closest friends. The lack of empathy of Abby, even towards some of her own friends, is what keeps Abby from gaining any clear moral victories. That said, Ellie herself alienates her own friends and by the end nearly does the unforgivable by killing Abby, who has been weakened and unwilling to fight by months of slavery. She just barely stops herself from [[JumpingOffTheSlipperySlope killing a weakened and unwilling to fight Abby]] when she has a flashback of Joel, mirroring Abby's own paternal flashbacks. In the end, regardless of who one might root for, both are empty, broken shells from a bloody CycleOfRevenge.
* ''Franchise/FarCry'':
** Discussed in ''VideoGame/FarCry2'' with the "Infamy" tape. [[BigBad The Jackal]] talks about how to break a man you need to show them how terrible taking a life is and how much you relish in killing. You need to turn into a person's personal monster and the more they fear you the better you get. But he also warns that you have to remember it's all posturing, and if you get lost in the violence you become less of a man, more of a beast, and it can be fatal. His speak partially becomes a game play mechanic with the Reputation stat, where the farther you go in the story, the greater your infamy; mooks will panic and make stupid mistakes far more often at the mere ''sight'' of you, but the {{NPC}}s will look upon you with increasing disgust no matter how many civilians you save.
** ''VideoGame/FarCry3'''s protagonist, Jason Brody, can either fit this trope to a T or (at least partially) subvert it. While on vacation with his girlfriend, his two brothers, and a couple of mutual friends, they get captured by pirates on the tropical Rook Island. Jason manages to flee with the help of his older brother Grant, who is murdered by the pirates' leader during their escape, while the rest are being held for ransom or to be sold into slavery. Jason stumbles upon the local natives, the Rakyat, who have been fighting the pirates for years, albeit without much success. Jason tries to free his friends, and slowly but surely turns from a regular guy into a pretty badass jungle warrior, gradually learning (unlocking) new skills that make him an ever more efficient killer. Not only that, but Jason also starts to doubt more and more if he can ever return to his old life, until at the end of the game - instead of going home with his friends - he has the choice to kill them, remain on the island, and fully embrace the path of the warrior.
** ''VideoGame/FarCry4'': All the major cast members start off trying to do some things moral and right, only to become just as cold-blooded and ruthless as the people they fight against; this includes [[spoiler:Pagan Min, as you find out during the GoldenEnding.]][[note]]DLC reveals Pagan was always AxCrazy, but he did care for Ishwari in his own way - before ruining their relationship by continuing to obsess over killing her husband instead of protecting her.[[/note]]
** This is undoubted what happens in ''VideoGame/FarCry5'' canonically: though the Deputy does their best to stop Joseph’s terror, they end up being subjected to his brainwashing and converted into one of his minions in [[VideoGame/FarCryNewDawn the sequel]].
* ''VideoGame/{{Manafinder}}'':
** An NPC asks Lambda is she's willing to kill a Nomad, and if she states that she's prepared to do so, the NPC warns her that doing so will make her like a beast. However, the other response, that she's "been there and done that," implies that she already killed someone in the past.
** Illia believes that [[spoiler:if Lambda receives her siblings' blessings and becomes an immortal leader for the Settlement, the latter will eventually become DrunkOnPower like King Vikar.]]
* In ''VideoGame/PuzzleQuest'', the main character falls into this in the bad ending, effectively replacing the villain of the story.
* ''VideoGame/PhantomBrave'' features a character like this. His name is Sprout, and he knew that he was absorbing the BigBad the more and more pieces of it he killed. He thought that he could control it, and when he couldn't, he killed himself and the parts of the BigBad that were fusing with him. This HeroicSacrifice weakened the BigBad for the heroes to fight.
* In ''VideoGame/DisgaeaHourOfDarkness'', main villain Archangel Vulcanus believes demons are pure evil and angels are pure good (untrue in Disgaea) and seeks to destroy the demons. This blinds him to his own evil actions, [[spoiler:including provoking war between Earth and the Underworld and enlisting demon assassins]].
* In ''VideoGame/KnightsOfTheOldRepublic'', we are told that this is what happened to the Jedi Knights Revan and Malak during the Mandalorian Wars prior to the first game. Kreia explicitly states as much in the second game: "As Revan and Malak fought the Mandalorians in battle after battle, they grew to despise weakness, just as the Mandalorians did. In the end, the Mandalorians had taught them through conflict. Shaped the Jedi."
** We also get a bit of {{foreshadowing}} on Bastila when she's in her full-on KnightTemplar mode, talking about how a Jedi must "harden their hearts" and "do what is necessary" to fight the Order's enemies.
** And [[VideoGame/StarWarsTheOldRepublic 300 years later]]: [[spoiler:The newly-freed and still-alive Revan (''very'' long story) decides the best way to pay back the Sith Emperor for that AndIMustScream imprisonment is by coming up with an army of {{Killer Robot}}s that will kill ''anyone'' with even a trace of Sith blood...roughly 97% of the Empire's citizens and quite possibly a few trillion Republic lives as well.]] So much for spending all that time maxing out the blue side of your KarmaMeter on the first two games, and NiceJobBreakingItHero for the Republic players...
*** And then in 'Shadow Of Revan' he's decided that both the Empire and Republic need to be destroyed...Along with anyone else who gets in the way of his plan to resurrect the Sith Emperor via the same ritual the Emperor used to achieve immortality.
*** [[spoiler:Turns out? There are actually TWO Revans. One good, and one evil. In Revan's misguided attempts to subtly brainwash the Emperor into growing a conscience between their torture sessions, the Emperor was able to pick apart his mind's angry, weakened mental defenses until it eventually ripped apart. As for the Emperor, he did grow a desire to raise a family... who he promptly abused and tortured until they became AxCrazy maniacs, one of whom turned to Dark Side because his desire for revenge against his father consumed him, just as his father always wanted.]]
* ''Franchise/FinalFantasy'':
** In ''VideoGame/FinalFantasyIV'', the elder of Mysidia uses this phrase to warn Cecil that he could fall into this trap until he willingly sheds his darkness.
** In ''VideoGame/FinalFantasyThe4HeroesOfLight'', Rolan--the world's [[TheChosenOne original Hero of Light]]--fought alone and ultimately took much of the darkness Chaos spread into his own heart, which was compounded by the loss of his dragon companion. He becomes a MisanthropeSupreme and sics his golems on any human visitors, then attacks the party and inadvertently causes a TimeCrash when they release the darkness.
** At the end of ''VideoGame/FinalFantasyXIV: Stormblood''[='s=] 4.0 Main Story Quest, that storyline's BigBad, Zenos, accuses the [[PlayerCharacter Warrior of Light]] of being this, always striving to find the next fight, living to fight and slay his foes. This ends up rearing its head hard in ''Shadowbringers'' where [[spoiler:the Warrior of Light's continued slaying of Lightwardens, greater Sin Eaters whose aether converts the next nearest living thing into one like a parasite, dangerously brings them close to becoming a Lightwarden themselves.]]
* Creator/NipponIchi occasionally does this straight (particularly with [[spoiler:[[VideoGame/Disgaea3AbsenceOfJustice Aurum]]]]), but is more often likely to apply this trope ''literally'' -- several characters have wound up as demons simply by killing a lot of them.
** Special mention goes to Prier of ''VideoGame/LaPucelle'', [[spoiler:because this is her ''canonical ending''.]]
* Donovan from ''VideoGame/{{Darkstalkers}}'' is a straight example, as he's a dhampir whose vampire blood caused him to slaughter his whole hometown, so he cursed it and longed for a life of peace; though while he hunts the Darkstalkers in order to protect humanity so as not letting them experience the same trauma, in his ending in ''Night Warriors: Darkstalkers Revenge'' he succumbs to his dark side in order to protect [[MoralityChain Anita]] and restore her emotions, and in a what-if instance, becoming the vampire Dee in the process.

** B.B.Hood inverts it, as she is already unhinged enough that she ''enjoys'' her job of slaughtering Darkstalkers. This is actually the entire reason why she, being based after Little Red Ridding Hood, is part of the roster of a fighting game where most fighters are monsters: humans '''can''' be monsters as well.
* In Terminal Reality's awesome monster hunting game ''VideoGame/Nocturne1999'', the protagonist, the Stranger, straddles the line of this trope without really going over it. He has an intense hatred of literal monsters, but he will begrudgingly work with them when the situation calls for it, such as by getting inside information from the [[FrankensteinsMonster reanimated mobster Icepick]] or working side-by-side with the [[HalfHumanHybrid dhampir]] Spookhouse agent Svetlana Lupescu. On the other hand, the retired Spookhouse agent Hamilton Killian vaults over this trope at a running pace with a pole: when his wife was [[TheVirus infected by a vampire,]] causing both herself and their unborn child to become undead, Hamilton, already a monster killing machine, went completely over the edge, unable to tolerate the presence of even ostensibly good "monsters". In the game, he sinks to the point of [[spoiler:trapping the Stranger in his estate, subjecting him to a series of lethal traps and captured monsters. His justification? The Stranger and Spookhouse in general have obviously become "monster lovers" for working alongside individuals like Svetlana and Icepick, rather than mercilessly killing them.]]
* Parodied in ''VideoGame/Left4Dead'': the graffiti in one safehouse reads "WE ARE THE MONSTERS" in large letters, and has a few scathing replies underneath it, including: "No, that would be the zombies", "Have you even looked ''OUTSIDE''", and "I hope you are dead now."
** "I miss the internet."

** A book in ''VideoGame/TheElderScrollsIVOblivion'' starts with a ShoutOut to the famous Nietzsche quote, "He who enters Oblivion allows Oblivion to enter him". Particularly true when you consider [[spoiler:the hero of that game ''canonically became [[MadGod Sheogorath]]''.]]

** Becomes a plot point in ''VideoGame/TheElderScrollsVSkyrim''. When the Dragonborn inquires with the Greybeards about [[spoiler:[[BrownNote Dragonrend]]]], Arngeir warns against it as learning Shouts means you must in part become the concept they are summoning, and [[spoiler:Dragonrend]] was conceived by people who lived under the harsh tyranny of the Dragon Cults - it is the metaphysical concept of pure hate and the Dragonborn may well become evil if they learn it[[note]]Nevermind the Dragonborn may well be the mortal champion of several Daedric Princes and a fully-paid up member of the [[MurderInc Dark Brotherhood]] at this point, but at the end of the day, [[EvilVersusOblivion it's them or]] ''[[DestroyerDeity Alduin]]''.[[/note]].

* ''VideoGame/{{Fallout}}'':

** In ''VideoGame/Fallout4'' the Mechanist incident manages to happen ''again'', but on a larger scale. In the ''Automatron'' DLC, a new Mechanist creates a robot army to protect the people of the Commonwealth from Raiders and other threats. Unfortunately, due to her [[AIIsACrapshoot Robobrain lieutenants thinking]] that the best way to prevent human suffering is to KillAllHumans, her robots go on a killing spree across Massachusetts while a new Raider gang called the Rust Devils reprograms them for their own purposes, and she remains blissfully unaware of all of this unless the [[PlayerCharacter Sole Survivor]] explains the situation.
* In ''VideoGame/{{Penumbra}}: Black Plague'', after learning a big lesson about the Tuurngait being [[spoiler:the original inhabitants of earth who liked mankind but hid because mankind was becoming violent,]] and completing some trials to show that [[spoiler:you understand that the Tuurngait are not evil,]] you contact the outside world and [[spoiler:reveal the location of the mine, and request that they kill them all.]] Then again, we never get proof that they aren't ''lying''...
** Ironically, the PC comments that his actions are a dark inversion of this trope: [[spoiler:having spent his entire life as an obedient follower, only to realize the worth of his individuality and free will through the various bastardly but insightful humans he meets, he decides that while saving the Tuurngait would be akin to a monster sympathizing with another monster, committing genocide despite the lessons he has learned is the only way to prove that he is not brainwashed, he is the one making this choice, and he is a real human. Unlike his friend, who is also as obedient as he once was and will likely burn an entire race to extinction just because someone told him to.]]
* The Church in ''VisualNovel/{{Tsukihime}}'' is known as being fanatically zealous about killing non-humans. Other characters imply, and we have even seen, that there are some demon hybrids/vampires who are neutral or good. The Church does not care, so it does not tend to get along with those like the Tohnos (hybrids, but avoid inversion), Arcueid (vampire, but kills vampires and is too tough for them to beat), and the Nanayas, who only targeted the Inverted. Notably, the only Church characters we see are a bit heretical for not blowing everything up first and then covering it up.
** It's not surprising for them to be heretics considering that the Church is repeatedly stated to have no influence in Japan -- since any members of the Church are the only representatives of it for dozens, if not hundreds, of miles, it's pretty safe to act as they please.
* [[ArmiesAreEvil Blackwatch]] from ''VideoGame/{{Prototype}}'' is about as evil as they come, fighting a merciless viral threat that doesn't care for the laws of war or human rights. Conversely, our player character Alex Mercer starts off real sociopathic and very slowly develops a conscience. Mostly, it is implied, by consuming people who have one.
* In ''VideoGame/ShadowOfTheColossus'', you [[spoiler:end up absorbing the colossus essences, culminating in becoming a demon yourself]]. Granted, later on, you [[spoiler:are reborn as a baby, but still...]]
* ''VideoGame/TalesOfVesperia''. The guild-wide FreudianExcuse doesn't excuse the Hunting Blades from acting worse than the "monsters" they hate so much.
** Yuri himself skirts this trope and is well aware that he almost falls into this. Ironically the one who ''did'' fall into this is [[spoiler:Sodia. Her own VigilanteExecution of Yuri basically made her into what she had always despised him for. Yuri ends up slapping sense into her when he comes back.]]
** The FinalBoss skirts the edge of this as he's so bitter due to past experiences that the main party has to prevent him from destroying the whole human race.
* ''VideoGame/TalesOfTheAbyss'' has a character, who in the past was forced to [[WhereIWasBornAndRazed destroy his homeland]] when he was eleven. That incident, along with finding out how the [[PropheciesAreAlwaysRight Score]] and people who know the "closed" parts had a part to play it, horrified him so much that he devoted his life to [[ScrewDestiny ending the Score]]. [[spoiler: Thing is? He's the ''BigBad'' for a reason: starting with the very fact he ''recreates'' the very incident that set him down this path with, to all intents and purposes, ''his own son''. And then his idea of "saving" the world is destroying it and replacing it with ImmuneToFate replicas. Said "son" goes on to be the one to stop him.]]
* In ''[[VideoGame/SoulSeries Soul Calibur IV]]'', Maxi has let his hatred of Astaroth consume him to such a degree that he's willing to use the soul-consuming sword his friends have been desperately trying to destroy to fight him. [[spoiler:In his ending, he's even willing to take up the sword against Astaroth with the knowledge that his friends will have to fight him afterwards.]]
* ''Franchise/MegaMan''
** By the time of ''VideoGame/MegaManZero'', ''VideoGame/MegaManX'' admitted to no longer caring about the enemies he fought. What's worse was that if it weren't for the ContinuitySnarl between the two series, he [[spoiler:would've become a full-out Maverick KnightTemplar.]] X, however, was savvy enough to realize this and took himself out of the fight [[spoiler:by acting as a living seal for the Dark Elf]] before he could go over the edge.
** Dr. Weil, the BigBad of the ''Zero'' series, is a straighter example. For all the acts of revenge he pulls on both humanity and the Reploids, he completely ignores the fact that he has become what he hates the most: a Maverick, in all definitions of the word.
** In ''VideoGame/MegaManZX'', the manner in which the ArtifactOfDoom, Model W, sows conflict and destruction in the world - and in doing so, grows stronger - exists at the point of intersection of this trope with TheVirus. If fighting monsters (both literal and metaphorical) ultimately causes you to become a monster - with Model W [[MoreThanMindControl accelerating the process]] - then those who fight ''you'' will ''also'' become monsters; apply recursively. This never-ending cycle is explicitly pointed out late in the second game. Appropriate, given who Model W used to be...
* ''VideoGame/ShadowComplex'' flirts with this in the subtext. The main character notes that killing has become easier for him, and he even gains a suit of the very same PowerArmor the enemies use, making him identical in appearance to them.
* Samus Aran of the ''Franchise/{{Metroid}}'' universe almost succumbs to this on a couple of occasions.
** The 3rd chapter of the manga describes an early recon mission she has as a [[CowboyCop Galactic Federation Police Officer]] on the planet of Jigrad. She and two of her squadmates save a group of slaves from the Space Pirates. When confronted by Samus, the last remaining Space Pirate pleads with her to show mercy. Driven by her memories of her homeworld K-2L being mercilessly razed by the Space Pirates, Samus is about to murder the last Space Pirate in cold blood when the sound of a small girl crying snaps her out of her rage. Shortly thereafter, the small child thanks Samus for saving her, and Samus tells her that she saved her as well from becoming just as much of a merciless killer as the Space Pirates.
** Also the ending of ''VideoGame/MetroidIIReturnOfSamus''. Samus is charged with the task of eradicating the Metroids once and for all. After destroying the [[FinalBoss Metroid Queen]], [[spoiler:Samus finds a newly hatched Metroid. Despite knowing that Metroid is a Chozo word for "ultimate warrior", she still can't bring herself to kill a child. Said child Metroid ends repaying her the favor by providing the EleventhHourSuperpower at the final battle in ''VideoGame/SuperMetroid''.]]
*** Also goes even further when you realize that this small mercy not only saves her in ''Super Metroid'', but also ''VideoGame/MetroidFusion'' as well.
* ''Franchise/MassEffect'' has [[CowboyCop Garrus Vakarian]] do this. He originally quit C-Sec to join Shepard's team because of all the red tape, as he says that it shouldn't matter how he got the job done as long as he did it. In the first game, his personal mission involves finding an organ-harvesting doctor who got away from him - Garrus's first instinct is to kill him on the spot ("I'd harvest your organs first, but we don't have the time.") Shepard can either encourage him or convince him to at least try to take him alive.
** In the [[VideoGame/MassEffect2 sequel]], his loyalty mission has him tracking down the only member of his vigilante squad to live through an ambush (considering that he was a {{Turncoat}}), wanting to kill him. Shepard has the option to cooperate or block Garrus's shot and have the guy tell him that he's a dead man walking.
** Liara almost does this as well as her quest for revenge on the Shadow Broker for [[BerserkButton trying to hurt Shepard]] causes her to [[BreakTheCutie turn from a sweet and innocent archaeologist to a ruthless information broker]] who barely trusts anyone and threatens people in the same way her mind-controlled mother did two years before. She even alienates Shepard, [[UndyingLoyalty the one person she risked everything for]], when s/he finally comes back from the dead. Ultimately, she eventually averts this...kind of. [[spoiler:After killing the Shadow Broker, she becomes the Shadow Broker, but vows to use the information to help Shepard fight [[EldritchAbomination the Reapers]] and will use that motivation to keep herself honest.]]
** [[EldritchAbomination The Reapers]] have this as one of their special powers. Indoctrination is an effect that slowly alters the minds of everyone in their vicinity to be more compliant towards their suggestions and assume their way of thinking. This effect even persists if they are dead, making even studying their remains dangerous. It seems very likely that [[spoiler:this happened to the Illusive Man, who studied the Reapers for years and eventually thought it was a good idea to implant reaper technology into his own body, which caused him to simultaneously fight the Reapers and attempting to do the very same thing he wants to prevent them from doing.]]
** ''Shepard'' can go this route if you play a strict Renegade.
*** The best way to live up this trope as Shepard is to play ''VideoGame/MassEffect1'' mostly as TheParagon, then in ''VideoGame/MassEffect2'', have them slowly slip into Renegade territory, still resisting giving into [[KnightTemplar Cereberus' advances]] but clearly getting more aggressive and less cooperative with the Alliance and the Council, but still doing the right thing. Then, finally, in ''VideoGame/MassEffect3'', turn Shepard into a vengeful killer and all-around {{Jerkass}}, culminating in Shepard going from a heroic guardian of life into the sort of person who hatefully criticizes the people who refuse to help him/her, threatens and assaults innocents to get them to cooperate, commits a minimum of [[spoiler:two genocides, betrays the people and even possible lovers or best friends who trust them, and ends up, more likely than not, murdering all synthetic life in order to accomplish their goals.]] It's all done in order to [[SaveTheWorld Save The Galaxy,]] and life in general, but knowing that a Paragon Shephard could do the same without the cruelty makes it incredibly difficult to stomach.
** ''VideoGame/MassEffectAndromeda'': The angara are very concerned about this in their war with [[ScaryDogmaticAliens the kett]], which given they've been at it for eighty years is a serious concern, and their resistance operates its battle tactics accordingly. The Roekaar do not share this concern, and are perfectly willing to cross lines even the kett won't to get rid of all aliens everywhere. Ryder can often point out they sound like their hated enemies, but it never stops them, just making them slightly more irritable.
* ''VideoGame/InjusticeGodsAmongUs'' applies this to the heroes of the DC Universe: in an alternate timeline, after killing Joker for destroying Metropolis and causing the death of Lois Lane, Superman establishes a dictatorship with the goal of not allowing another Metropolis. Eventually, it becomes twisted into a desire to subjugate and conquer: part of his plan after crossing the MoralEventHorizon is to cross over into the main DC timeline, conquer its Earth, and forcibly take its Lois as his bride. Ironically, this is exactly what Joker wanted: [[StrikemedownwithALLofyourhatred prove that]] everything in life is [[StrawNihilist meaningless]].

*** Likewise, Batman fears becoming this more than most, which is why he strongly holds on to the ThouShaltNotKill rule, but adhering to said rule has earned him derision from Robin, Superman, and Wonder Woman, who all frequently chide him for not having the conviction to kill.
* ''Videogame/BatmanArkhamAsylum'' has, along with Batman himelf (and Joker does his best to try pushing him over the edge in the game), there is [[spoiler:Arkham's warden Quincy Sharp. After he had spent years amongst the Asylum and their inmates, his mind had slowly turned murderous and insane, developing another secret personality: "The Spirit of Arkham". Before the events of the game, he had tried to kill Joker in his cell (failed badly), and had thought of lobotomizing Harley and burning Ivy alive.]]
** Batman in ''Videogame/BatmanArkhamCity'' calls Ra's al Ghul on this, stating that he becomes everything he fought against. Considering Ra's doesn't care about innocent victims of his activites and tries to kill Talia, his daughter, to make Batman accept his place, Batman is right.
* ''VideoGame/SuikodenTierkreis'' makes this recursive. You can take down the BigBad the easy way by sacrificing the lives of all your allies or look for another, harder way to beat him. [[spoiler:On the hard path, you find a copy of the tablet that lists the names and magical affinities of all your allies. Every name on it except the one under the "[[StandardizedLeader Tenkai Star]]" has been burned off, since they sacrificed their lives to stop a villain before this one, except for the leader who became the fellow you're now fighting. On the easy path, [[ShootTheShaggyDog you replace him.]]]]
* In ''Franchise/DragonAge'', the Grey Wardens are an order of warriors, rogues, and mages dedicated to fighting [[OurOrcsAreDifferent the darkspawn]]. To do so, they ingest darkspawn blood, making them more powerful and allowing them to sense the darkspawn. This also slowly turns them into darkspawn-like creatures. The Wardens are also known for their ruthlessness in fighting the darkspawn, as they have no qualms against killing people who have been infected with the darkspawn taint, although they are nowhere near as brutal as the darkspawn.
** Loghain Mac Tir is the main antagonist of the game and is so paranoid that he refuses to ask for help when Ferelden is on the verge of defeat, and sparks a civil war, simply because the king was going to ask for help from the Orlesian Empire, which had invaded Ferelden years ago. As such, he leaves the king to die at the hands of the darkspawn during the Battle of Ostagar, along with every Grey Warden allied with him, because he's paranoid that it's handing Ferelden back over to the Orlesian Empire, when the entire country is about to be destroyed. In the process of this all, he becomes everything that he hates, and never realizes it -- some Ferelden citizens will speak in hushed tones that he now resembles the very Orlesians he once threw out of the country.
** In order to fight the darkspawn, the dwarven smith Caridin created an Anvil that allowed him to [[spoiler:painfully transform dwarves into golems. He stuck to volunteers at first, but the king ordered him to start using the poor, criminals, and the king's political enemies. Eventually, Caridin realized what [[MyGodWhatHaveIDone he and the king had become]] and refused to do any more of this, and the king ordered Caridin's apprentices to turn him into one.]]
*** Branka -- was she a monster before, or did she become one due to her obsession with the Anvil? The epilogue shows that anyone who gets hold of the anvil becomes pretty inhuman (indwarven?) with its use. To get it, Branka went that extra step and mutated her own people, who hunted monsters with her, involuntarily into monsters by allowing them to be raped and forced to eat the flesh of their friends. These monsters give birth to the monsters they hunted and Branka used them to set off the traps guarding the anvil.
* In ''VideoGame/DragonAgeII'', Anders has a very literal case of this, as he has voluntarily allowed the spirit of Justice from Awakening to possess him, but his anger has warped Justice into a force of vengeance against the Templars, and Anders has become very much a WellIntentionedExtremist.
** The entire storyline is built on this. [[spoiler:The leaders of both factions eventually give in to their demons. Knight-Commander Meredith, who had fought blood mages all her life (okay, and an ArtifactOfDoom), calls for the Rite of Annulment ordering the death of every mage in the city for the action of one rogue mage; and First Enchanter Orsino, who resorts to BloodMagic to put down Meredith and the templars who had oppressed them. They both [[JumpingOffTheSlipperySlope jump off the slippery slope]] for what they see as the [[WellIntentionedExtremist right reason]]. The major irony is that they both ignore the most important flaw in their own factions; Orsino allows a serial killer mage to go unchecked because he went so far that he broke new ground, and Meredith uses dangerous anti-magical techniques to instill absolute order -- including demonic possession and end up literally becoming monsters that are the opposite of their class; Orsino uses blood magic to become a hulking corpse bruiser with a slippery-quick center (Reaver and Assassin), and Meredith uses a cursed sword in the name of the Maker, not realizing that she just used magic to jump twenty feet in the air and re-activate the city's antipersonnel robots (Battlemage and Demon Summoner).]] It really fuels the game's relentless GreyAndGrayMorality.
* The southern Grey Wardens as a whole nearly succumb to this trope in ''VideoGame/DragonAgeInquisition.'' [[spoiler:After Corypheus uses a false Calling to make them believe they are all dying, they ally with a Tevinter mage to summon an army of demons that they will use to slay the remaining Old Gods. Unfortunately, the ritual they use to summon said demons also leaves them completely subservient to Corypheus.]]
* Considering the back story of ''VideoGame/{{Killzone}}'', the Helghast could be seen as these. Fleeing to a DeathWorld after losing a war trying to resist the [=UCN=]'s tyranny, they became as bad as the very people they fought.
* In ''VideoGame/BlazBlue'', Kokonoe has a seething hatred of Terumi Yuuki. In her attempts to bring him down, though, she has committed some acts [[MoralEventHorizon that are earning her the ire of the fanbase,]] like treating [[TheWoobie Lambda-11]] as if she's nothing but an inanimate tool. She is aware of this fact (doesn't even try to cover it up with justifications and does feel bad about some things, like the aforementioned Lambda treatment) and notes to herself that she has crossed the point of no return a long time ago.

** [[GovernmentConspiracy The Patriots]] are a good example of such an issue: They were initially formed to essentially eliminate [[AncientConspiracy the Philosophers]] and [[UtopiaJustifiesTheMeans replace it with The Boss' teachings]]. Unfortunately, soon after that, Zero, Para-Medic, and Sigint ended up becoming corrupt, and eventually became the very thing that they attempted to remove.

** In ''VideoGame/MetalGearRisingRevengeance'', WellIntentionedExtremist [[BigBad Senator Armstrong]] wanted to undo the damage caused by the Patriots and [[ActionPolitician make America great again]], but ended up becoming just like them (except slightly more honest). Like Zero he was TheSocialDarwinist who wanted to socially engineer American civilization, but this time [[AsskickingLeadsToLeadership through violence]] rather than manipulation.
* ''VideoGame/DiabloIII'':
** Averted by the playable Demon Hunter, who is utterly ruthless in their fight against all things demonic, yet doesn't let it compromise their goal of protecting the innocent. This isn't a given for Demon Hunters in general, however. The short story ''[[http://us.battle.net/d3/en/game/lore/short-story/demon-hunter/1#read Hatred and Discipline]]'' describes it as every Demon Hunter having to navigate the threshold between good and evil, with it being all too easy to lose control over their fear and hatred, and "cross over to the other side".
** Tyrael invokes this in regards to Zoltun Kulle, whose efforts to create the Black Soulstone drove him to murderous megalomania. At the end of ''Reaper of Souls'', he worries that [[spoiler:[[PlayerCharacter the nephalem]], who has amassed immense amounts of power to destroy some of the world's greatest threats and become TheDreaded to angels and demons alike, could well become this trope by virtue of being a mortal who has the capacity to be seduced by evil and become yet another threat to humanity. Given that the nephalem had a massive hate-on for Adria and was likely willing to [[RevengeBeforeReason kill her before getting some mission-critical information from her]], Tyrael is more than a little justified in his concerns.]]
** Malthael fell headfirst into this in the expansion pack, ''Reaper of Souls''. In his efforts to destroy all traces of demons, he became just as much of a threat to humanity and the angels as Diablo himself, to the point of [[spoiler:using the Black Soulstone with Diablo's soul inside to try to annihilate all humanity, and then take the Prime Evil into himself in his last-ditch attempt to destroy the Nephalem]].
** Referenced in the FlavorText from the legendary sword ''Monster Hunter'': "Be wary when you fight monsters, lest you become one."
* In ''VideoGame/DiabloIV'', the Blackweald Company mercenaries were hired to fight against the demon Astaroth when he rampaged across Scosglen. Witnessing the abyssal fires he unleashed broke something inside the mercenaries, and after Astaroth's defeat they became obsessed with continuing his work.
* ''Franchise/{{Tekken}} 6'''s Jin Kazama quotes Nietzche word for word after his final encounter with Lars. As far as Jin is concerned, however, he will do whatever it takes to end his bloodline, including becoming just as evil/hated as Azazel, who was responsible for most of the conflict in the Mishima bloodline.
* ''VideoGame/CityOfHeroes'':
** The player can fall from a Hero to a Vigilante by taking some morally dubious actions, and eventually fall to Villain. Fortunately, you can pull a HeelFaceTurn.
** Among NPC factions, this is part of [[CorruptCorporateExecutive Countess Crey's]] backstory: she was originally an idealistic young woman out to Right Great Wrongs. [[TheDarkSideWillMakeYouForget However, in her effort to gain enough power to do this, she lost sight of why she wanted the power]].
* Subverted in ''VideoGame/TouhouSeirensenUndefinedFantasticObject'', the 12th game of the ''Franchise/TouhouProject'' series, with the origin story of Byakuren Hijiri, a youkai hunter who came to genuinely sympathize with youkai and eventually converted herself into one. In the same game, Sanae Kochiya is warned that if she continues to hunt youkai with such zeal, she will play this trope straight. There has been mention of [[CuteWitch Marisa Kirisame]] possibly converting herself into a youkai in a bid for power and immortality, though it hasn't happened.
* Happened to [[spoiler:Fain and his followers]] during the [[HopelessWar Elder Wars]] in ''VideoGame/{{Lusternia}}''. They start out employing methods that the other Elders found [[KnightTemplar questionable]] and end up JumpingOffTheSlipperySlope and ''eating'' their fellow Elders to [[CannibalismSuperpower fuel the war effort]] - which happens to be the same threat presented by their foes, The Soulless.
* It's lightly hinted at in ''VideoGame/KingdomHeartsII'' that [[TheHero Sora]] is slowly falling into this, based on how much more aggressive, ruthless, and rude he is toward the enemies than he was in the first game. Then again, fighting the forces of Darkness themselves can take its toll on people, especially when you have [[spoiler:dozens of people inside your soul]].
** WordOfGod says this outright, also stating that Anti-Form is a product of it.
*** [[spoiler:In ''VideoGame/KingdomHearts3DDreamDropDistance'', Sora finally succumbs to the darkness in his heart, and nearly becomes a [[GrandTheftMe Xehanort clone]]. Even worse is that he is the FinalBoss of the game. He gets better, thanks to Riku]].
** [=DiZ=][=/=][[spoiler:Ansem the Wise]], who, in his efforts to make sure that neither TheHeartless nor the Organization XIII takes over the universe, relies on kidnapping, psychological manipulation, and playing the YouHaveOutlivedYourUsefulness card on his Nobody allies. At least he regrets it in the end before he [[spoiler:got blown up and killed, [[DisneyDeath for a while.]]]]
* In ''VideoGame/{{Nier}}'', the protagonist develops an all-consuming hatred for the Shades after [[MaouTheDemonKing The Shadowlord]] kidnaps his daughter (or sister, [[OneGameForThePriceOfTwo depending on the version]]) at the end of the first half of the game, and spends most of the second part killing Shade after Shade in order to find her. Then, at the end, we get TheReveal: [[spoiler:Shades are actually the souls of the true humans, and only a fraction of them are truly evil: Nier has thus spent a majority of the game slaying thousands of innocents and bringing humanity closer and closer to extinction just to save ''one'' person]]. The point is especially hammered down in the NewGamePlus, where [[spoiler:the players (but not the characters) can now understand the language of the Shades and see the backstory of the bosses, Shadowlord included, that you've been mercilessly cutting down. Nier is Robert Neville.]]
* ''VideoGame/SpecOpsTheLine'' -- Walker becomes increasingly violent, and commits unmitigated ''war crimes'' in his pursuit to kill John Konrad, the man who rules the ruined city of Dubai. [[spoiler:However, Walker does [[MyGodWhatHaveIDone realize what he has done]], through flashbacks and hallucinations.]]
* In ''VideoGame/{{Syndicate}}'' (2012): The CIA weren't quite heroes in the first place, but they were one of the last holdouts of governmental force against the syndicates. However, with funding at critical levels, they turned into the Independent Intelligence Agency, which is itself a syndicate. The infobank entry directly mentions becoming the monster they used to fight.

* Three very literal cases in ''VideoGame/DarkSouls'':
** Artorias clashed with the dark monsters of the Abyss, earning the title of Knight Artorias the Abysswalker. [[spoiler:Unfortunately, he was eventually overcome by the Father of the Abyss, Manus, becoming the very kind of twisted creature he fought for so long.]]
** The [[MeaningfulName Abyss Watchers]], as their name indicates, are subject to this. They were formed to fight the Abyss, but eventually fell to it, much like [[spoiler: their founder or inspiration, Artorias]].
** Darkeater Midir, like everyone else who made it their mission to fight the Abyss, became corrupted by it. He hasn't completely lost his mind by the time you meet him, but Shira asks you to kill him before that happens and he starts attacking the Ringed City instead of defending it. During his boss battle, he will relent and fully accept the power of the Abyss once his health is depleted enough.
* ''VideoGame/{{Bloodborne}}'' explores this trope in combination with AndThenJohnWasAZombie: [[HunterOfMonsters Hunters]] are sent out to combat the spreading [[OurWerewolvesAreDifferent scourge of beasts]], and since people afflicted with the scourge get more bestial and more dangerous the further their affliction has been allowed to progress, it's just frankly better if the Hunters can take down the afflicted during the early onset of the plague. However, the less beast-like a Hunter's prey becomes, the more likely it is for them to experience SanitySlippage, JumpOffTheSlipperySlope, and start attacking humans still unafflicted with the scourge. Prime example here would be Father Gascoigne who simply attacks you because "you'll be one of them, sooner or later."
** There's also a faction of Hunters, lead by Eileen the Crow, who are referred to as [[WhoWatchesTheWatchmen the Hunter]] [[HunterOfHisOwnKind of Hunters.]] Their stated mission is to hunt down Hunters who succumb to this trope. Ergo, Hunters hunt monsters while the Hunter of Hunters hunt monsters who hunt monsters... And if you botch up her questline, then Eileen herself will succumb to this trope, meaning you'll have to put her down, making you the Hunter who hunts the- you know what, I'm already cross-eyed enough as it is, so let's just leave it at that.
** In a literal application of the trope, it's also strongly implied that humans who forsake their own humanity and higher values to the point that they, in their madness, turn their weapons on their own kind are more susceptible to the scourge as they become more likely to fall prey to their own base, beastly minds and instincts, which subsequently makes them turn into beasts themselves. Prime example, once again, being Father Gascoigne who wolves out partway through your fight with him.
* In ''VideoGame/BioShockInfinite'', the [[LaResistance Vox Populi]] purport to be noble freedom fighters who oppose the violently racist ''and'' fascist Founders who rule over Columbia. Years of fruitless fighting, though, have gradually caused them to degenerate into a band of marauders who fight out of sheer blind hatred for their enemies. The first move of their leader, Daisy Fitzroy, upon gaining power, is to shoot and scalp a CorruptCorporateExecutive. After [[spoiler: she dies]], the Vox continue their fight throughout the game's climax, tearing up the city streets and killing or even enslaving anyone who looks like a Founder, all while their new leader rants that everything now belongs to them.
** This is a common theme in all the series. In the first game, Andrew Ryan tried to create a society free of government but became a tyrant in order to protect his dream and combat Frank Fontaine's rise to power. In the second game, Sofia Lamb tried to make an absolutely selfless society where no one stood above anyone else, but had to become a dictator thanks to her being the [[OnlySaneMan only non-crazy person in Rapture]]. [[spoiler:Comstock may also count. The atrocities he committed in way caused him to become a religious zealot after being baptised to cleanse his soul, but instead of atoning for his sins, he justified them as righteous and committed even grander atrocities in the name of his egocentric religion.]]
** The most heartbreaking example, however, is Elizabeth, from ''VideoGame/BioshockInfinite''. In the main game, she's a motivated, intelligent, compassionate woman, and [[spoiler: killing Booker at the end to cut off countless timelines in which he becomes Comstock breaks her heart.]] In the ''BioshockInfinite/BurialAtSea'' DLC, however, we see that [[spoiler: she's taken her drive to influence space-time events to eliminate any many Comstocks as possible to a bloodthirsty, self-centered extreme. The Booker you've been playing as throughout the episode is actually a Comstock who accidentally killed his timeline's baby Elizabeth when that Booker tried to take her back, and was so [[MyGodWhatHaveIDone consumed with guilt]] that he asked the Luteces to bring him to a new timeline, where he could forget about ever having been Comstock and just quietly live out the rest of his days. He adopted Sally after years of living in Rapture and was a good father to her; he did everything in his power to rescue her when she was abducted to become a Little Sister, which is why he jumped at the chance to find her when Elizabeth offered him information as to her whereabouts. This Comstock was atoning for his sins and hadn't posed a threat to an innocent person for a long time, and even sincerely apologizes to Elizabeth when he remembers his past, but the fact that he's a Comstock at all means she sentences him to a horrific death. This comes back to bite her, however, once she's [[MyGodWhatHaveIDone consumed by guilt for using Sally as a pawn and then leaving her for dead.]] When she first [[ConscienceMakesYouGoBack comes back to Rapture to save Sally,]] she has a conversation with her auditory hallucination of Booker, and he subtly calls her out for becoming just as evil as the man she's been killing over over and over. Keep in mind that her hallucination openly identifies himself as a manifestation of her subconscious so she's just talking to herself, meaning that she knows what she did was wrong.]]
** Some of the splicers in the first two games are a more literal example. Some of them were normal peopl who started spicing to ''fend them off'' and got addicted to ADAM and started mutating. Thus, they became crazed splicers themselves.
* In ''VideoGame/CastlevaniaLordsOfShadow'', Gabriel Belmont is a knight of the Brotherhood of Light, charged to protect and defend innocent mortals against monsters. His quest revolves around trying to resurrect his murdered wife, Marie. Towards the end of the game, he learns upon confronting the Lord of the Necromancers, [[spoiler:Zobek]], that he has a dark side within him so terrible that the Lord of the Necromancers found it surprisingly easy to control him in his sleep and [[spoiler:kill Marie]]. The main game ends with Gabriel given a chance for redemption, but the DownloadableContent reveals that during his quest to contain the Forgotten One, [[spoiler:he is forced to become a vampire in order to enter the Forgotten One's prison, and gets corrupted by the Forgotten One's power upon claiming it for himself]]. By the time TheStinger rolls around, [[spoiler:Gabriel has a ThatManIsDead attitude and proclaims "Eu sunt {{Dracul|a}}!"]]
** ''VideoGame/CastlevaniaSymphonyOfTheNight'' implies this is why Richter Belmont has sided with evil and is lord of the titular castle. According to him when encountered in Dracula's Throne Room, a Belmont has a single fight against Dracula and then must surrender their job to the next descendant, so Richter decides to circumvent this by resurrecting Dracula to fight for eternity and maintain his status. [[spoiler: Subverted, however, because Richter is being possessed by Shaft]].
** This is an actual plot point in ''VideoGame/CastlevaniaCurseOfDarkness''. [[spoiler: Death, masquerading as the priest, Zead]] plots to revive Dracula by pushing Hector to chase after Isaac and take his vengeance on him, expecting that Hector will succumb to Dracula's curse by willfully murdering his former companion in a vengeful rage and make him the perfect vessel for Dracula's return. St. Germain very vaguely hints at this being why Hector should back off of his [[RoaringRampageOfRevenge vengeful quest]] but doesn't give any real specifics.
* By the end of ''VideoGame/SaintsRowTheThird'', STAG has lost any moral high ground it might have had, having [[spoiler:declared martial law, carried out abduction and detention without trial (on Shaundi), rigged a major monument to blow in a terrorist-like manner]] and, in one ending, trying to [[spoiler:level the whole city]] to get at the Saints. In the other ending, the one who sent them hangs a lampshade on this, pointing out that our favourite {{Villain Protagonist}}s acted more heroically and asking who the people are going to support after that.
** The Playa/Boss and the Saints themselves. [[CleanUpTheTown Playa originally joined up with the Saints in the first game to do what they can to curb the constant gang violence after being caught in the crossfire,]] but in the process, he/she quickly degenerates into a complete sociopath and the Saints follow suit, becoming just as insane, greedy, and destructive as any gangs they've ever fought if not more so. Then reversed in the subsequent games, where they slowly regain their heroism.
** By ''VideoGame/SaintsRowIV'', [[spoiler:Cyrus Temple, the leader of STAG, has gone from fighting monsters to becoming one, forming a terrorist cell in the Middle East with the intent of destroying Washington DC on the basis that the Saints "ruined America".]]
* In ''VideoGame/TheWonderful101'', [[spoiler:The GEATHJERK are those that fight monsters: They came from 1,500 years in the future to destroy Earth because in their time, Earth has founded the Greater Galactic Coalition which, using Wonderful technology, invaded Jergingha's planet; and so they try to restore peace to the galaxy by destroying Earth... and doing so by becoming a space terrorist organization and using Wonderful tech in the final boss battle. It all becomes one giant TimeyWimeyBall once you consider Earth probably invaded them as revenge for invading us in the present, and that it would create a time paradox because destroying Earth would have prevented the destruction of ther planet, but in turn eliminating the very reason GEATHJERK was created in the first place!]]
* ''VideoGame/{{RefleX}}'' features [[spoiler:the Phoenix / ZODIAC Ophiuchus]], which is so bent on destroying the hostile ZODIAC units, which humans describe as "Winged Menaces", that [[spoiler:it ends up unapologetically destroying a horrifying percentage of Earth and humanity, causing it to be labeled as simply yet another winged menace.]]
* In, ''VideoGame/DwarfFortress'', the players will often be forced to resort to rather extreme solutions to survive some of the most dangerous events and monsters. That being said, the community being what it is, those events and monsters are less of a cause and more of a convenient excuse for the methods.
* ''VideoGame/CallOfJuarezGunslinger'': near the end of the game, [[spoiler:Silas realizes that in his quest for revenge, he has killed more people than the men he was hunting ever did.]]
* The story of the Animatronics that hunt for you in ''Franchise/FiveNightsAtFreddys'' (or at least most of them). Throughout the 1980s, [[BigBad William Afton]] kills numerous children at the Freddy Fazbear's Pizza joints: Majority, if not all of his victims go on to possess the robots inside the pizzeria, and start killing night guards in a quest for vengeance, as one of the only things they know about William is that he was a night guard at one point. And while the dead children are trapped within their bodies claiming victims for around 8-10 years, William escapes punishment... until he decides to go visit an abandoned Freddy's. [[LaserGuidedKarma It ends poorly]].

-->'''If you're reading this - Don't look for me.'''
* The VillainProtagonist RabidCop known as "F-8" in ''VideoGame/NeedForSpeed Rivals'' spends the entire game trying to bring down the aggressive street racers in Redview County and their leader, [[WellIntentionedExtremist "Zephyr"]], who started the illegal street racing scene and reckless driving in the county after posting videos of his driving online and challenging others to beat him as a protest against Redview County's GovernmentConspiracy. [[spoiler:[[TheBadGuyWins By the time F-8 brings down Zephyr,]] [[PyrrhicVictory he gets fired for]] [[PoliceBrutality his overtly aggressive tactics]] in bringing down the racers. F-8 then becomes the new leader of street racing in Redview County, challenging racers online in the same way as Zephyr.]] However, this is only through cutscenes, since you still play as [[spoiler:[[KarmaHoudini a still-hired]]]] F-8 once the Cop storyline is over.
* The endings of some ''Franchise/SilentHill'' games take this literally.
** One ending of ''VideoGame/SilentHill3'' ends with [[spoiler:Heather, possessed, killing Douglas]].
** For one ending of ''VideoGame/SilentHill4'', [[spoiler:a possessed Eileen kills herself]].
** For ''VideoGame/SilentHillOrigins'', [[spoiler:Travis is the Butcher]].
** An ending of ''VideoGame/SilentHillHomecoming'' involves [[spoiler:two Pyramid Heads turning Alex into one of them]].
*** For some less literal examples, [[VideoGame/SilentHill2 James]] is revealed to have [[spoiler:murdered his wife, technically reversing the order of this trope]], [[VideoGame/SilentHill3 Vincent]] suggests that Heather [[spoiler:has actually been killing human beings and ''enjoying it'']], Harry Mason in ''VideoGame/SilentHillShatteredMemories'' turns out to be [[spoiler:a ghost and figment of Heather's imagination]], and an especially horrible ending of ''VideoGame/SilentHillDownpour'' reveals that [[spoiler:Murphy is the one who raped and murdered his own child, in addition to killing two other people]].
* In ''VideoGame/NeverwinterNights2'', [[spoiler: Ammon Jerro]] fits this trope due to his efforts to prevent the freeing of a SealedEvilInACan, which are extreme enough that the protagonist believes him to ''be'' the canned evil itself for quite a while. The player can [[WhatTheHellHero call him out on this]].
* A bit literally in ''VideoGame/{{Undertale}}'', if the player character goes on the Genocide Run, [[spoiler:Asgore ''won't even recognise you as human'']].
** To flip perspectives entirely, there's also Undyne, who exhibits FantasticRacism against humans after they defeated and imprisoned monsterkind in the Underground. Monsters view humans as inherently aggressive and much more willing to kill, and also recognize that monsters simply can't match the power of a human SOUL. Undyne's bloodthirstiness is a very unusual trait among monsters, and [[spoiler: she is the only monster to naturally produce their own Determination, just like humans can]]. Her drive to defeat humans ends up with her showing many qualities that monsters attribute to humans.
* In ''VideoGame/Doom2016'', the Doomguy has apparently been changed by his journey(s) to hell and exposure to demonic energies. The first thing he does upon waking is rip his way out of thick iron chain and crush a zombie's head with his (pentagram-inscribed) bare hands. His armor now bears strange runes, and can only be worn and activated by him. And, in addition to being hyperviolent, he can absorb demonic energies and runes that lore indicates would kill or cripple a normal human. Which, clearly, he no longer is.
* ''VideoGame/DeepSleepTrilogy'' opens with "And if you gaze for long into an abyss, the abyss gazes also into you." Aside from the [[TheDarknessGazesBack obvious]], [[{{Foreshadowing}} the significance]] on using a line from the trope namer becomes clear in the endings: [[spoiler:[[AndThenJohnWasAZombie you've become a shadow person]], and your only chance of escaping is to rob a stranger's life and puppeteer their body in the waking world, or you can choose not to lose the rest of your own humanity and remain in the deep sleep for eternity]]. Where this scene takes place? [[spoiler:The exact same hallway where you first saw a shadow person... except YOU are the monster]].
* ''VideoGame/Section8: Prejudice'': The Spear do have a legitimate grievance with the US Empire [[spoiler:trying to exterminate them after they had achieved their purpose of cleansing the galaxy of alien life]], but their plan to kill millions of civilians as vengeance isn't the answer, as Corde points out when he fights their leader.
* ''VideoGame/{{Destiny}}'' features the story of Dredgen Yor. [[FallenHero Before becoming the most hated guardian to have ever lived]], he was once known as Rezyl Azzir. During the Dark Age, he was revived by his ghost and became a Risen. A civil war soon started after tensions between factions after misusing their light and he became a champion from this war. He watched The Last City grow and pondered about the threats on the Moon called the Darkness. He ventures out of the city and becomes an enemy of the Fallen. Using his trusty hand cannon Rose, he managed to kill off a Kell and track many Fallen Raiders. He then heads off to the moon on his own and meets Xyor, the Betrothed who [[ProphecyTwist prophesied he would fall one day. Fall he did...]] he gets overtaken by Darkness and his Rose became Thorn. He then kills off many innocent guardians and destroyed the settlement of Palamon and killing Jaren Ward, owner of the Last Word hand cannon. He lets Shin and his Ghost live as he anticipated that Shin would hunt him down and he would corrupt him as well. It did not end well for Dredgen Yor as he would be killed by Shin.
* In ''Franchise/TheElderScrolls'' series, this is common in both [[OurVampiresAreDifferent Vampire]] and [[OurWerewolvesAreDifferent Werewolf]] hunters. Because both are [[ViralTransformation diseases]] which can be transmitted via any wound inflicted by an infected individual, literally becoming what they once hunted is a common fate for these hunters who aren't outright killed. Most carry disease curing potions or items on their person for immediate consumption in the event they become infected. (Both can be cured easily within the first few days of being contracted, but if the diseases progress, they become [[FindTheCure much more difficult]].)
* [[CelestialParagonsAndArchangels Namm]] from ''VideoGame/NexusClash'' is a literal god of this trope. Winning ultimate victory against his archenemy [[ManipulativeBastard Tlacolotl]] and the [[EldritchAbomination other]] Dark Powers is all that matters to him, and he's prepared to do so over the corpses of innumerable demons, evildoers, neutrals and bystanders who are clearly (to him) enabling evildoers [[AccompliceByInaction by inaction]], insufficiently dedicated good-aligned people and angels, and in at least one case [[spoiler:another angelic deity]] who he didn't think was loyal enough to the cause. What's worse, Tlacolotl really ''is'' dangerous enough that it's hard to be sure that this isn't a setting where TheExtremistWasRight.
* ''VideoGame/ThisIsThePolice2'': [[spoiler:Jack, Lana, and even Lily]] go off the deep end trying too hard to enforce justice in a city/town that doesn't remember what justice is. [[spoiler:Jack]] is the only one who learns to live with themselves becoming a monster - because the others are dead by their hand.
* In ''VideoGame/RatchetAndClank2002'', protagonist Ratchet desires to become a superhero like Captain Qwark and Ace Hardlight, but is disillusioned when he finds out that Qwark has been working for Drek all along, and almost dies at the hands of Qwark's trained "pet". [[FaceHeelTurn His reaction]] is to chase after Qwark with the intent of killing him, while coldly dismissing Drek's threats against the galaxy and [[KickTheMoralityPet abusing Clank]], leading to the latter [[TheReasonYouSuckSpeech pointing out that Ratchet has a problem]] in one of their fights, and is teetering on the MoralEventHorizon. It isn't until Qwark is finally defeated when Ratchet has a HeelRealization after seeing Gorda City in ruins from an invasion he could've prevented easily, and that mindless obsession with revenge pushed Ratchet down the path of villainy, like Qwark and Ace before him. He spends the rest of the game as TheAtoner.
* ''Franchise/ResidentEvil'':
** A central theme in ''VideoGame/ResidentEvilTheDarksideChronicles'', which even features the quote in promotional material for the game. The "Operation Javier" scenario is the story of Jack Krauser's StartOfDarkness, as his experience fighting bio-weapons twisted him from a loyal partner into a man obsessed with wielding the same power that [[CareerEndingInjury crippled him]].
** ''VideoGame/ResidentEvilRevelations'' chronicles the downfall of the [=FBC=], the original government agency charged with fighting bio-terrorism. [[spoiler: Director Morgan Lansdale and several of his subordinates became convinced that the world wouldn't take the threat of Bio-terrorism seriously without a second disaster like Raccoon City. To this end, they collaborated with terrorists to carry out an attack that destroyed a major city in hopes the world governments would take notice]].
* ''VideoGame/ClockTower'' plays with this in the second game during Helen's D and A endings, where it's revealed [[spoiler: that Professor Barton is the Fake Scissorman due to his claim that the danger of studying criminal psychology is you get drawn into its darkness. He goes on to tell Helen that he was drawn in "by his evil soul" and questions Helen as to whether she's strong enough to prevent it happening to her too. Helen immediately says she's better than that.]]
* ''VideoGame/BloodstainedRitualOfTheNight'' introduces this concept as a plot point, that absorbing too many shards from fallen demons can hasten the curse Miriam and Gebel are experiencing and make it more likely for them to be possessed by evil. [[spoiler: The second ending, which requires you face and kill Gebel after acquiring the Zangetsuto, implies that Gremory can possess Miriam easily due to the number of shards she's collected for this reason.]]
* ''VideoGame/TheNewOrderLastDaysOfEurope'':
** The United States of America can resort to increasingly draconian and brutal foreign policy in the name of combating the fascist menace posed by the Third Reich and the Japanese Empire. However this results in political and social instability, and risks the last democratic nation becoming little better than their enemies. The Organization of Free Nations styles itself as TheFederation, a mirror of NATO in OTT, but in reality it is headed by a ControlFreak USA that uses the organization as a naked extension of their power, and it might just collapse altogether depending on how things play out. This tendency is most apparent in the South African War, which is a mirror conflict to the Vietnam War in OTT, except fighting fascists instead of communists, and the Americans can quite easily botch the whole thing up, sparking the African Crisis.
** One of the potential unifying warlord states in Russia is Omsk, a fortified citadel ruled by militant ultranationalists who will stop at ''nothing'' to enact the [[FinalSolution Great Trial]], their plan to [[GuiltFreeExterminationWar utterly annihilate the German civilisation with nuclear and chemical "revenge" weapons]]. So great is their vindictive madness that not even the spectre of nuclear apocalypse will turn them away from this goal.
** Israel exists in this timeline, and one potential direction it can go is towards the cause of [[BecameTheirOwnAntithesis building a Jew supremacist ethnostate and forcibly driving out all non-Jews from the country to keep it pure]] for the true "MasterRace". Really, the real NightmareFuel that makes ''The New Order'' is how it presents the psychological and ideological consequences of a Nazi victory as well as the physical human cost: worldviews based on hatred and Darwinism become validated by the Nazis' success, [[DownerEnding and even a people as peaceful and benevolent as the Jews are corrupted and made to accept the brutal logic of their oppressors]].

* ''VideoGame/BattleForWesnoth'': The protagonist of ''Descent into Darkness'', Malin Keshar, at first just wants to fight orcs to protect his hometown. He then turns to darker and darker magics to do so, actively hunting down the orcs. willingly fights humans who stand in his way, and eventually becomes more of a threat to humanity than the orcs ever were as the mighty lich Mal Keshar.
* In ''VideoGame/SekiroShadowsDieTwice'', Karmic Debt is a constant theme haunting Wolf, a Shinobi who takes lives by the dozens in his quest to save the master he's utterly loyal to. Hanging over Wolf's head because of this heavy karmic debt is the risk of starting to enjoy killing for the sake of killing instead of doing it because it's his duty, which would turn him into an immensely powerful demon called Shura. [[spoiler: If Wolf forsakes his duty to save Kuro because of his father's commands, he severs the last thing keeping his murders moral- his negative karma overflows and he becomes Shura and massacres the entire Ashina territory.]]
* Tragically, [[spoiler:Oersted]] in ''VideoGame/LiveALive'' sets out to slay the Lord of Dark, [[spoiler:but the deaths of his friends, being manipulated into assasinating the King of Lucrece and becoming a pariah because of it, and the spiteful suicide of his supposed LoveInterest Princess Alethea, almost all of this product of the betrayal of his supposed best friend (who set his path of ruin in motion out of jealousy), prove so traumatic that he suffers a total psychotic breakdown and becomes the reborn Lord of Dark himself, set to declare war on all of reality.]]

* In ''VideoGame/{{Nier}}'', the protagonist develops an all-consuming hatred for the Shades after The Shadowlord kidnaps his daughter at the end of the first half of the game. It's really shown in the NewGamePlus where [[spoiler:the players can now understand the language of the Shades, AKA the souls of the true humans, and see the backstory of the bosses you've been mercilessly cutting down. Nier is Robert Neville.]]

%%% Zero Context Example entries are not allowed on wiki pages. All such entries have been commented out.

* This trope is heavily at play in ''VideoGame/TheLastOfUsPartII'', [[spoiler: which is natural given the CycleOfRevenge between Abby, who [[YouKilledMyFather lost her father to Joel in the last game]], and Ellie, after [[NoHoldsBarredBeatdown Abby brutally kills Joel as payback while Ellie helplessly watches]]. From this point onward though, Abby [[VengeanceFeelsEmpty feels empty and conflicted]]; she only engages in fighting Ellie when given no choice, and finds healing and redemption through [[FamilyOfChoice helping Yara and Lev escape the Seraphites.]] However, she still commits many brutal acts [[WithUsOrAgainstUs against anyone she perceives to be an opponent]]. Ellie meanwhile sadistically hunts Abby down, going from killing [[PayEvilUntoEvil her ruthless Wolves teammates who assisted in her murder of Joel, and almost killed her in turn]] to threatening if not killing Abby's absolute closest friends. She just barely stops herself from [[JumpingOffTheSlipperySlope killing a weakened and unwilling to fight Abby]] when she has a flashback of Joel, mirroring Abby's own paternal flashbacks.]]

* This trope is heavily at play in ''VideoGame/TheLastOfUsPartII'', [[spoiler: which is natural given the CycleOfRevenge between Abby, who [[YouKilledMyFather lost her father to Joel in the last game]], and Ellie, after [[NoHoldsBarredBeatdown Abby brutally kills Joel as payback while Ellie helplessly watches]]. From this point onward though, Abby [[VengeanceFeelsEmpty feels empty and conflicted]]; she only engages in fighting Ellie when given no choice, and finds healing and redemption through [[FamilyOfChoice helping Yara and Lev escape the Seraphites.]] However, she still commits many brutal acts [[WithUsOrAgainstUs against anyone she perceives to be an opponent]]. Ellie meanwhile sadistically hunts Abby down, going from killing [[PayEvilUntoEvil her ruthless Wolves teammates who assisted in her murder of Joel, and almost killed her in turn]] to threatening if not killing Abby's absolute closest friends. She just barely stops herself from [[JumpingOffTheSlipperySlope killing a weakened and unwilling to fight Abby]] when she has a flashback of Joel, [[NotSoDifferent mirroring Abby's own paternal flashbacks]].]]

* This trope is heavily at play in ''VideoGame/TheLastOfUsPartII'', [[spoiler: which is natural given the CycleOfRevenge between Abby, who [[YouKilledMyFather lost her father to Joel in the last game]], and Ellie, after [[NoHoldsBarredBeatdown Abby brutally kills Joel as payback while Ellie helplessly watches]]. From this point onward though, Abby [[VengeanceFeelsEmpty feels empty and conflicted]]; she only engages in fighting Ellie when given no choice, and finds healing and redemption through [[FamilyOfChoice helping Yara and Lev escape the Seraphites.]] Ellie meanwhile sadistically hunts Abby down, killing [[AndYourLittleDogToo every one of her friends who gets in her way, even when they're completely defenseless]]. She just barely stops herself from [[MoralEventHorizon killing Abby]] when she has a flashback of Joel.]]

* The story of the Animatronics that hunt for you in ''VideoGame/FiveNightsAtFreddys'' (or at least most of them). Throughout the 1980's, [[BigBad William Afton]] kills numerous children at the Freddy Fazbear's Pizza joints: Majority, if not all of his victims go on to possess the robots inside the pizzeria, and start killing night guards in a quest for vengeance, as one of the only things they know about William is that he was a night guard at one point. And while the dead children are trapped within their bodies claiming victims for around 8-10 years, William escapes punishment... until he decides to go visit an abandoned Freddy's. [[LaserGuidedKarma It ends poorly]].

* ''VideoGame/{{Tekken}} 6'''s Jin Kazama quotes Nietzche word for word after his final encounter with Lars. As far as Jin is concerned, however, he will do whatever it takes to end his bloodline, including becoming just as evil/hated as Azazel, who was responsible for most of the conflict in the Mishima bloodline.

* ''VideoGame/TalesOfTheAbyss'' has a character, who in the past was forced to [[WhereIWasBornAndRazed destroy his homeland]] when he was eleven. That incident, along with finding out how the [[PropheciesAreAlwaysRight Score]] and people who know the "closed" parts had a part to play it, horrified him so much that he devoted his life to [[ScrewDestiny ending the Score]]. [[spoiler: Thing is? He's the ''BigBad'' for a reason: starting with the very fact he ''recreates'' the very incident that set him down this path with, to all intents and purposes, ''his own son''. And then his idea of "saving" the world is destroying it and replacing it with ImmuneToFate replicas. Said "[[CloningBlues son]]" goes on to be the one to stop him.]]

* ''VideoGame/InjusticeGodsAmongUs'' applies this to the heroes of the DC Universe: in an alternate timeline, after killing the Joker for destroying Metropolis and causing the death of Lois Lane, Superman establishes a dictatorship with the goal of not allowing another Metropolis. Eventually, it becomes twisted into a desire to subjugate and conquer: part of his plan after crossing the MoralEventHorizon is to cross over into the main DC timeline, conquer its Earth, and forcibly take its Lois as his bride. Ironically, this is precisely [[StrikemedownwithALLofyourhatred what the Joker wanted all along]], as [[StrawNihilist he]] wanted to prove Superman's morals wrong, just as he did to [[Film/TheDarkKnight Harvey Dent/Two-Face]], [[WesternAnimation/BatmanMaskOfThePhantasm Andrea Beaumont/The Phantasm]], and [[WesternAnimation/BatmanUnderTheRedHood Jason Todd/Red Hood]].

** In ''VideoGame/MetalGearRisingRevengeance'', WellIntentionedExtremist [[BigBad Senator Armstrong]] wanted to undo the damage caused by the Patriots and [[ActionPolitician make America great again]], but ended up becoming just like them (except slightly more honest). Like Zero he was TheSocialDarwinist who wanted to socially engineer American civilization, but this time [[AsskickingEqualsAuthority through violence]] rather than manipulation.