Two weeks after the events of Guilty Gear X, the story opens with I-No, a servant of That Man, delivering Happy Ending Override to the main characters of the previous game. I-No's ambush on the May Ship causes Dizzy to be thrown overboard and go missing, instigating May and Johnny to look for her; other characters are also visited by I-No and given deliberately misleading information in attempt of manipulating them. At the same time, Ky Kiske discovers a mysterious organization creating robotic clones of himself, while Millia's story focuses on her quest of revenge against Eddie, who seeks another host as Zato-ONE has died. Slayer watches the activities of the other characters from the sidelines and gives advice to them, namely Sol and Millia. Oh, and Jam is on the hunt for the mysterious arsonist who burned down her restaurant she built with Dizzy's bounty reward.
As is the case with the previous installment, XX builds upon the cast with four brand new characters:
New characters
- Slayer, the vampiric founder and original leader of the Assassin's Guild, who finds himself brought out of retirement.
- Zappa, a seemingly innocuous man from Australia who is, unbeknownst to him, actually possessed by a mulitude of seemingly malevolent spirits.
- Bridget, a young, up-and-coming bounty hunter from England who might be more than meets the eye.
- I-No, the Final Boss. A sadistic servant of That Man who has a strange connection to Axl Low.
Additionally, the game sees the return of both Kliff Undersn and Justice via unlockables.
This work shows examples of:
- Bad Future:
- One shown in an XX drama CD, where Ky's death results in a future where Dizzy takes over for her late mother as the leader of the Gears, and most of the cast dies by the end. Thankfully, I-No, spurred on by That Man, saves Ky for her own interests, bringing a much more positive end to the Crusades.
- I-No's stages take place in future Babylon, on top of a ruined cathedral in XX.
- Bowdlerise: The original translation for the story mode of XX and #Reload, done by Majesco, borders on "Blind Idiot" Translation at certain points. Due to this, several key plot points and character nuances ended up Lost in Translation, like the explanation behind Axl's time warping abilities, Venom's loyalty for Zato actually being something more, and subtle hints towards Bridget's gender dysphoria that would be elaborated on in later games.
- Capcom Sequel Stagnation: Guilty Gear XX has a honor of being one of the true contenders that challenges Street Fighter II in term of re-releases, having 5 different revisions after the original game. That's only one revision behind Street Fighter II (the latest being Super Street Fighter II Turbo HD Remix) at the time of Accent Core Plus R, although Capcom has since widened the gap by releasing Ultra Street Fighter II in 2017.
- Combo Breaker: If the Burst gauge is full, Pressing the Dust button and any other attack button at the same time while you're being attacked will activate a Blue Psyche Burst, sending the opponent flying. If the Burst hits, the Burst gauge fills up by 30%, but if it misses, the gauge is emptied, and the opponent can punish it.
- Contractual Boss Immunity: When fought at the end of Arcade Mode, I-No is immune to Instant Kills.
- Early-Installment Weirdness: Even in this series-codifying release, the first version of XX had quite a few quirks compared to later versions, but nonemoreso than it's version of Robo-Ky. Rather than the extremely quirky short tempered robot we know and love, vanilla Robo-Ky is portrayed much as he was in X Plus: another version of Ky Kiske with some of the same moves but in a far creepier, somewhat disturbing way.
- His default stance had him hunched over, his voice lines had stutter and his character select and VS screen portraits were simply edits of regular Ky's to turn him into an admittedly creepy robot.
- He had bright green skin-plating instead of the duller grey that later Robo-Kys had.
- He retains the voice of Takeshi Kusao rather than having another VA perform him.
- He has the traditional Tension gauge instead of the Electric gauge.
- He uses moves similar to Ky's but undeniably off, including an inverse version of EX Ky's Crescent Slash, a Flash Step version of EX Ky's Ground Slash (called Impala Hunt), and two moves wholly unique to him in the form of Ray Divider and Aegis High.
- He's an unlockable character along with Kliff and Justice rather than being a part of the base roster.
- Franchise Codifier: Guilty Gear XX and its revisions put together a template from the previous games for future games of the series. The Burst Combo Breaker system is first introduced, the existing mechanics are further fleshed out (like adding the aerial version of Throws and Dust Attacks for more air combo opportunity), and the Story Mode has a proper Story Branching and fully-voiced dialogues for each character. This game's playable character roster is still the most iconic out of all games, so is its Announcer Chatter ("Heaven or Hell? Duel 1. Let's rock!").
- Interquel: Guilty Gear XX Accent Core Plus is technically counted as such since it was released after Guilty Gear 2: Overture and its new story mode bridges the gap between XX and Overture's stories.
- Lag Cancel: The Roman Cancel mechanic returns in this game. In addition, performing a Roman Cancel during certain parts of some moves' animations will result in a Force Roman Cancel. Force Roman Cancels only cost 25% of your Tension instead of the usual 50%, and can be done on whiff. The moves that can be Force Roman Canceled vary from character to character, and includes some moves that can't be Roman Canceled under normal circumstances, such as projectiles.
- Mechanically Unusual Fighter: Pretty much all of the newcomers have some unusual feature that sets them apart.
- I-No has a New Kakyoin-esque hoverdash that puts her in the air.
- Slayer has a forward and backward teleport instead of a forward dash and backstep. His gatling combo routes are also much more limited than the rest of the cast.
- Bridget lacks true Heavy Slash normals. Instead, pressing any direction + Heavy Slash places a yo-yo at a certain spot on the screen. The properties of certain specials and Overdrives depend on the yo-yo's position, and it can be recalled by pressing the Heavy Slash button again.
- Robo-Ky became this after his rework in #Reload. Instead of a Tension meter, he has an Electric Gauge, which fills up when you stand in a power mat, which can be placed by using his Sweep. In addition, he has a Heat gauge that has to be carefully managed — many of his normals are enhanced at 80% Heat, but if he reaches 100%, he overheats, causing him to take unblockable damage. The Heat gauge is emptied whenever you use forward + Heavy Slash.
- A.B.A relies heavily on her command throw/hitgrab to enter Moroha Mode which gives her an overall boost. However, while in said mode, her own health will drain whenever she makes contact with her opponent, be it through attacks or blocks. She also has a meter controlling the duration of Moroha Mode that slowly drains over time, with 30% of it being lost whenever she is knocked down.
- Medicate the Medium: Zappa seeks out the help of the miracle doctor Faust, believing himself to be suffering from a mysterious illness. However, his condition is actually the result of being possessed by seven different ghosts and that he just doesn't remember his possessions. Faust informs him that he cannot be cured as his condition is not physical in nature.
- Multi-Slot Character: Both Sol Badguy and Order-Sol, a.k.a. Sol from the Past, are playable fighters in this game's roster.
- Nerf: Faultless Defense Cancels technically still exist, but the ability to incorporate them into combos has been limited greatly. They're still a key part of some Advanced Movement Techniques, but the number of characters that can actually use them can be counted on one hand.
- Sequel Hook: Bridget's alternative ending in Accent Core has her returning to her home village only to be greeted by her uncle telling her that something has happened to her parents and that her twin brother has gone missing, setting up for a potential sequel story.
- Twins Are Special: The town Bridget was born and raised in believes that identical male twins will bring about misfortune and the superstition runs so deep that the younger twin must be either put up for adoption or put to death.
- Word Salad Title: The game's title got progressively longer and more ridiculous as each re-release adding an English word after the previous name, eventually settling on Guilty Gear XX Accent Core Plus R in 2012.
