* SugarWiki/AwesomeMusic:
** Prairie Rain Field.
** Lambda Server's Root Town, Carmina Gadelica
** Sigma Server's Root Town, Fort Ouph
* DemonicSpiders:
** Data bugged enemies get [[DegradedBoss downgraded]] from boss to standard enemy late in ''Outbreak''. It's not that they're particularly hard to beat (generally, beat them up, Data Drain them, beat them up some more); the problem is that using Data Drain that much repeatedly jacks up your infection rating, and hitting 100% gets you a NonStandardGameOver. Sure, defeating enemies without Data Drain or waiting long enough can reduce the infection rating. But if you're in the middle of a long dungeon with large numbers of data bug enemies, every fight is a risk for a Game Over.
*** One side mission for Terajima Ryoko is infamous for ''EVERY MONSTER PORTAL IN THE DUNGEON'' containing a Data Bugged enemy.
** Enemies that are able to heal themselves and others are incredibly annoying, as they can drag a fight for longer than the normal length. Even worse are the ones that can revive their allies as soon as they're killed.
* EnsembleDarkhorse:
** Mistral was extremely popular, so much so that [[spoiler:after she quits in ''Outbreak'', she shows up again near the end of ''Quarantine'' for the final battle.]]
** Skeith is far more popular than any of the other Phases. Fidchell was also liked because of his prophecy gimmick.
* FauxSymbolism:
** The relationship between Aura and Morganna in ''Sign'' is gone into further depth here, but Corbenik himself is a massive case of this, especially since he gets involved with the former two.
** Skeith's original version of it's staff was supposed to be a cross. It was changed into a "Q" to avoid controversy.
* GameBreaker: Proper use of the Lucky Shoes becomes this. They grant two spells - one to regenerate your HP, and one to regenerate your [[{{Mana}} SP]]. In boss fights, this drastically improves your survivability (as you don't need to heal nearly as often) while allowing you to spam your special attacks. Short of OneHitKill moves and the possibility of [[NonStandardGameOver terminal corruption from Data Drain]], you become close to unstoppable.
* HilariousInHindsight: The games were all hit with ItsShortSoItSucks, being that they are intended to be episodes of a larger game. Episodic gaming was pretty uncommon at the time, despite that several other games had been released as "Episodes" far before this game series was.
* ItsShortSoItSucks: Played with. The whole series is 60-80 hours long including all the side missions, a fair length. The ''problem'' is that each disk is only about 18-20 hours by itself and the whole thing could have been on one disk. Made even more apparent in hindsight considering the original IMOQ ''quadrilogy'' is shorter than the sequel G.U. ''trilogy'' (up to 120 hours across the three games).
* TheScrappy:
** Piros, mainly since having him in the party replaces the otherwise awesome BGM with a track of fanfares...
** Elk had many detractors due to his meek personality.
** Terajima Ryoko suffered a lot from late character syndrome, her personality being a carbon copy of Natsume's, and for being nasty to [=BlackRose=].
* SidetrackedByTheGoldenSaucer: Even though the game expects the player to go through each story mission dungeon, there's no rule that's stopping them from going to any random dungeon. This is also very helpful because if the next story mission is too tough for them, they can go to another dungeon to get more experience and reach a higher level. Not to mention, if the player is low on money or health items, they can go to the other dungeon for more of both. And they're trying to collect everything from the Ryu books, they'll definitely have to visit more dungeons than just the story related ones to find everything. The grunty raising is also an addicting distraction for some.
* ThatOneAttack: Magus' "Death And Rebirth" attack, which makes the fight a PuzzleBoss fight. It's the first fight in which something specific [[spoiler: in this case, destroy the leaves that it drops before the countdown hits zero]] is needed to be done to mitigate or prevent its effect, and the game doesn't give any advance warning about it. Fail to do what's needed? Guaranteed TotalPartyKill, no matter what level you are. Outside of that attack, though, Magus is one of the easiest phases.
* ThatOneBoss: About any of the four games has you fighting a Phase that can be very tough.
** Skeith is ridiculously tough, in part due to being the player's first experience fighting a Phase. You fight him at a very low level compared to any other Phase and won't have access to really powerful equipment; the fight will also teach the dangers and quirks of a Phase fight with the boss using unavoidable attacks and Data Draining one of your allies every now and then.
** Macha has an ability that causes everyone in your party to be charmed at the same time. Enjoy helplessly watching your party attack each other.
** Tarvos is an incredibly obnoxious boss: constantly switching between Physical and Magical Tolerance like Cubia's Core, casting magic spells that will run roughshod over your party, and possessing an attack that is a guaranteed 9999 damage (a OneHitKO) to one member of your party, making him a top contender for Skeith's title of worst boss in ''.hack''.
* ThatOneLevel: One side mission with Terajima Ryoko from ''Outbreak'' is utterly ''loathed''. It's the most notorious case of DemonicSpider in the entire series - with a dungeon so loaded with Data Bug enemies you are guaranteed to deal with one from ''every single portal'' - and Terajima's dialogue is almost entirely her sniping at [=BlackRose=].