* SugarWiki/AwesomeMusic: The DVD gives the option to turn off dialogue and leave only the music. Considering that said music was made by Music/YukiKajiura, did you really expect anything less?
** All the games feature great music by Chikayo Fukuda and the wailing vocalist Tomoyo Mitani performs the TearJerker song to close out the the first two ''G.U.'' games plus the awesome third song. She also did the vocals for Aura's theme in the first game and more. To top it off, ''.hack//Link'' also features a few of Kajiura's songs.
* BrokenBase: TheReveal of [[spoiler:Tsukasa]] as a girl. Some found it an interesting twist while others didn't.
* FandomRivalry: With ''Literature/SwordArtOnline'', due to both series having many similarities as taking place in virtual world [=MMORPGs=] but having different approaches to their themes and characters. However, some consider the two series to be too different to even compare.
* HilariousInHindsight: This wouldn't be the only time Creator/MitsukiSaiga voiced a character in a [[VideoGame/{{Pripara}} video game franchise]] [[spoiler: whose true gender isn't what we thought initially]], though [[spoiler: Hibiki]]'s personality and mannerisms are ''very'' different from Tsukasa's.
* ItWasHisSled: [[spoiler: The fact that Tsukasa's player is a girl]] is not that much a secret nowadays anymore.
* JerkassWoobie: Tsukasa, at first. He's cold and distant and tends to snap at and push people away, but when you know about his downright ''horrible'' childhood involving his mother dying when he was little and the abuse he'd been subjected to at the hands of his [[AbusiveParents rotten excuse of a father]], as well as all the other crap that happens to him as he's stuck in the game with no way of being able to log out, it's hard to not want to give him a hug. Plus, he does [[CharacterDevelopment grow out of the Jerkass part as time goes on]].
* MemeticMutation: [[https://www.youtube.com/watch?v=v956KJZZ-gY The Monkey Dance.]]
** "[[TotallyRadical This shindig looks like the bomb-diggity.]]"
** Considering B.T. frequently has chats with Sora, she was killed by him a few times in the game, and attacked by two player killers in a dungeon. This eventually becomes a joke in .hack//GIFT, where absolutely no one is surprised to see that B.T. was murdered ''yet again.''
** For about a decade, all you had to do is yell out "I'm stuck in the game!" or "I can't log out!" around anyone who has seen this show, especially in an MMORPG, to spark laughter, or joining in. Nowadays, it's been co-opted by a [[Literature/SwordArtOnline different franchise]].
* NightmareFuel: A few moments, despite being a non-action-heavy series.
** Tsukasa trains his Guardian to not make people comatose after he gets a dressing-down by Bear and Mimiru. It's first action in combat is to [[ThereIsNoKillLikeOverkill brutally whip a quartet of players who come after Tsukasa and preventing them from leaving, with the final shot of the episode being Tsukasa staring in fear as it keeps whipping the players even after they've stopped fighting back]].
** [[spoiler: Morganna's]] MindRape of Tsukasa with heavy abusive themes.
** [[spoiler: The first appearance of Skeith, the Terror of Death, in the final episode, and Sora being subjected to Data Drain. Even worse considering Skeith's Data Drain on Sora resulted in him being comatose for ''4 years''.]]
* ValuesResonance:
** A fair amount of the series is merely talking... about the implications of online escapism through virtual reality. While not just commentary on [=MMOs=] in general, there's now a whole section of the internet based on programs like [=IMVU=], [=VRChat=], and others where players are free to not only make their own online avatars, but the increased prevalence of VR headsets and even room set-ups means a player's motions can be transferred to the characters in game. And while SIGN is a series meant to take place in an action-based [=MMORPG=], the way many of the characters use it almost like a chatroom is similar to how [=VRChat=] and [=IMVU=] and others would be used later on down the road.
** The series also manages to touch a bit on parasocial relationships, given how few of the characters know each other in real life and how certain relationships between them are potentially being used to make up for failed relationships outside instead of supplementing them; an entire episode is centered around Bear wondering how far he wants to go in taking care of Tsukasa vs how he's distanced from his own real-life son, and Subaru is attacked by a supposed "fan" who both wants to emulate and prove dominance over her, and has the attraction of the Crimson Knight who has started taking his protection of "Lady Subaru" way farther than just playing a role in a game. Parasocial relationships and long-distance support to virtual avatars one's grown attached to became a common problem among the Vtuber community about 10-15 years later, where some interest is healthy and good for their livelihood but too much can create problematic obsessions and the lack of distinguishing between the popular friendly persona/avatar and the person they are outside of that.
* ViewerGenderConfusion: Macha is a girl. Though due to the lack of any clear feminine characteristics outside of being part purple, it's next to impossible to tell from watching the show alone. She has no voice either. (This is explained in tie-in novels to be because she communicates entirely via text, which in-universe players can see, but the viewer cannot.) In the original Japanese version she has one voiced line [[spoiler: because she vocally screams in a woman's voice when she's killed.]] This one line is left unvoiced in the dubbed version. It's only during .hack where she has a much more human and feminine model that actually speaks with a female voice that one would know.
* TheWoobie: [[NotSoWeak Subaru]] puts up with so much crap, and then it's also revealed that she's a WheelchairWoobie as well.
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