''.hack//Infection'', ''.hack//Mutation'', ''.hack//Outbreak'', and ''.hack//Quarantine''. These four games are each "chapters" of one massive game on the Playstation 2, sometimes collectively referred to as ".hack//IMOQ". They take place immediately after ''DotHackSign'', and form the core of the R1 storyline of the [[DotHack .hack]] saga. ''[[DotHackLiminality .hack//Liminality]]'' takes place concurrent to the games' story.

As the game begins, Kite logs into The World for the first time, his best friend Orca showing him the ropes. However, he soon witnesses Orca get attacked and Data Drained by a strange enemy known as "Skeith", who is chasing a white-haired girl who does not appear to be either an NPC or a player. Kite is whisked away by unknown forces before the same fate can befall him, and receives an item called The Twilight Bracelet, which allows him to use Data Drain himself. Learning that Orca's player has been in a coma ever since being attacked in-game, Kite begins a quest to find out what exactly is going on in The World and how to save Orca.

The games are complemented by a quartet of {{Light Novel}}s titled ''.hack//Another Birth''. These novels follow the same story from Kite's partner [=BlackRose's=] point of view. Events that [=BlackRose=] was not present for are skipped over in the novels, but they also detail what her offline life is like, and some things she does on her own when Kite's not around.

See [[Characters/DotHack here]] for character sheets.

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!!These games contain examples of:

* AdultsAreUseless: Averted. Though most of the heroes are teenagers or children, one of their greatest allies is [[spoiler:Lios, the head system administrator and employee at CC Corp]]. No one knows Helba's age, but she certainly acts like a woman in her twenties or thirties.
* AIIsACrapshoot: Morganna
* AmazingTechnicolorBattlefield: That weird landscape you are transported to when fighting the Phases. Corbenik actually gets two of them. [[spoiler:By the final battle with him, Cubia has grown so enormous that ''he'' serves as the battlefield himself.]]
* ArmorAndMagicDontMix: Wavemasters are only allowed to wear the lightest armor class.
* AuthorAvatar: Piros (or Piroshi) is based of game director and CyberConnect2 President Hiroshi Matsuyama.
* BarrierChangeBoss: Tarvos the Avenger and Corbenik the Rebirth in .hack//Quarantine. Fortunately, the game tells you what, if anything, every enemy you face is tolerant (immune) to by way of glowing orange text next to its lifebar.
* BlindIdiotTranslation: The first ''Another Birth'' volume has several glaring mistakes, such as getting Kite's and [=BlackRose's=] dialogue mixed up in their first meeting, and referring to Skeith as "Death" for most of the book (with a rather pathetic attempt at a HandWave when they switch over to his real name). Fortunately, the later volumes have a much better translation.
* BonusBoss: All four games have a bonus boss at the end of the game. All combine with LevelsTakeFlight, BonusDungeon and all are [[MarathonLevel Marathon Levels]].
* CallBack: Recreated events from ''DotHackSign.''
* CanonImmigrant: Tsukasa, Subaru and Sora can all be added to your party by the end of the fourth game. Macha in it's cat form from ''SIGN'' also appears in a bonus dungeon.
* TheCameo: A few ''[[DotHackSign Sign]]'' characters can be found in the game, though not in the main storyline.
* ChekhovsSkill: [[spoiler: Drain Heart]] in ''Quarantine.'' [[spoiler: Given to Kite at the beginning, then used by Corbenik at the end.]]
* ClimaxBoss: Skeith, Fidchell, and Macha, the only Phases other than Corbenik with any importance besides being a Phase, though Skeith moreso than the other two.
* CrypticConversation: Any conversation with Vagrant AI's or [[spoiler:Harold remnants]].
* CursedWithAwesome: Some who are aware of the Bracelet consider it an illegal item due to its GameBreaker nature, which also leads them to consider Kite a malevolent hacker.
* DangerousForbiddenTechnique: Data Drain. Using it on a regular enemy will reduce it to a pathetically weak form that can be beaten in one hit, and it is required in order to defeat hacked enemies. It will also occasionally net you some items. However, the more you use it, the more Kite's data gets corrupted, and the more negative side effects pop up... the worst of which is an instant GameOver.
** The technique becomes doubly dangerous in ''Quarantine'', when you start running into The Guardian from .hack//SIGN. It is difficult on its own, level 80 with high stats, but Data Draining it turns it into The Bracelet, the game's only level 99 monster part from the Phases and Cubia.
* DiscOneNuke: Sora's Blades in Outbreak. You can get them early on from a level 70 dungeon, and as long as you go with a party, you'll be fine, and you'll probably get other excellent equipment as well. They've got the "death" effect on them, which will save you a lot of trouble as you go through the game.
* DubInducedPlotHole: Mistral refers to her baby as being a boy but it's actually a girl. The same girl who becomes Mireille in DotHackLegendOfTheTwilight.
* EleventhHourRanger: [[spoiler: All of the coma victims joining the fight to eliminate Corbenik's Supreme Defense.]]
* EleventhHourSuperpower: In a villainous example, [[spoiler: Corbenik has Supreme Defense for his second form and ''Drain Heart'' for his third.]]
* EyesAlwaysShut: Natsume and A-20.
* TheFaceless: Morganna, the BigBad, has no form and is never seen nor heard ([[spoiler:except possibly during the final Corbenik fight, where it's suggested that Morganna itself is controlling the Phase]]). The Eight Phases act as its agents throughout the game, and are the most visible sign of its presence.
* FetchQuest: One of the more disliked aspects of the game was the need to go hunting for very specific Virus Cores to open new areas, which would only be dropped by certain enemies when Data Drained.
* FinalBoss: By the end of ''Mutation'', provided you know the backstory well enough, you know it could most likely be Cubia, Morganna, or Corbenik. [[spoiler: Cubia is taken care of right before Corbenik, and it seems Morganna took over Corbenik's body for his final form. Thus, the final boss is technically Corbenik, but Morganna got involved...somehow.]]
* HeroicSacrifice: [[spoiler: Elk throws himself into the path of Corbenik's Drain Arc]].
* IconicOutfit: Kite's signature red costume. It's noted in the novels that that shade of red is not actually available for players to choose, further emphasizing the "above the rules" nature of Kite's abilities. Vaguely alluded to in-game, since Kite becomes known for it (and no NPC wears the same shade of Red that Kite has).
* InterfaceScrew: Corrupted areas of the game have frequent bursts of static. A large amount of white noise is also a good indication that either Cubia or a Phase is about to show up.
* MarathonBoss: True to being a FinalBoss, Corbenik with three major forms.
* TheNameless: Morganna is never actually referred to as such in the games themselves, though it is in the novels.
** Except in [[spoiler:one of Aura's early messages to Kite, where you can pick the name "Morganna" out of the scrambled text]].
* NighInvulnerable: Any hacked enemy, as well as the Phases, must be Data Drained before any damage can be done to them.
** [[spoiler: Corbenik the 8th phase is the one exception due to the bracelet being destroyed in the fight with Cubia. However, he has Supreme Defense to fall back on]].
* OldSaveBonus: In addition to bringing over your characters exactly as they were at the end of the previous volume (likely with much better gear than the default if New Game is chosen), you get access to extra content and quests if you carry an old save over.
* [[OneGameForThePriceOfTwo One Game For The Price Of Four]]: Each of the individual games is full-priced, but they are all essentially the same game, with the same mechanics, setting, and characters. [[OldSaveBonus You can import saves from older games into the newer ones]] so you can continue exactly where you left off.
* TheOtherDarrin: Balmung was voiced by DougErholtz in ''Infection'' and then by Creator/CrispinFreeman from ''Mutation'' through ''Quarantine.''
* OohMeAccentsSlipping: Rachel when summoning spells or [[CallingYourAttacks calling her attacks]] doesn't speak in her accent.
* VictoryFakeOut: Corbenik pulls this on you, you get him to just low enough HP and he regains it all.
* VillainOverride: [[spoiler: Implied that Morganna did this to give Corbenik one last form far different than the other Phases.]]
* WhiteHairedPrettyGirl: Aura.
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