Guilty Gear X2 is generally considered the purest and/or most popular edition of the Guilty Gear (ギルティギア, Giruti Gia) series, beyond any doubt the most important creation of Arc System Works. Even though it brought back the eclectic excessive esthetics of its predecessors, Guilty Gear X2 provided gamers with a more technical approach.

It is considered by many to be the best 2D fighter ever produced, although it has suffered from severe balance issues ever since the first Guilty Gear game, and a lot of 2D fighting fanatics prefer less luxuriant graphics. It uses a gauge system, akin to Street Fighter Alpha's Super Combo techniques, allowing "super" specials and one-hit "Destroy" kills.

GGX2 uses six buttons, generally corresponding to a punch, a kick, a slash [weapon], and heavy slash [slower harder strike]. The fifth button taunts or greets the opponent, who thereby gains tension in his or her gauge. GGX2 also features a Dust button [which can be used to sweep enemies or propell them into the air to initiate air-combos.]

The main characters of the series are Sol Badguy, Ky Kiske, Potemkin, Millia Rage, Zato-1 [Eddie], May, and Potemkin. The main antagonist is Justice, a sentient robot "gear" system who resides at what appears to be the gates of heaven. Throughout the years, however, more characters gained prominence. GGX2's roster contains 23 characters. Although two versions of RoboKy exist.

The game's main slogan "Heaven or Hell, let's rock" fits very well with the overall musical theme of the game. Daisuke Ishiwatari's musical preferences permeate the game's presentation, characters, storyline, and even the names of the special moves yelled by the characters. "Ride the lightning!"

As mention above, several versions and re-editions of Guilty Gear XX exist. Most of which bring minor changes to the original. The main difference, usually, consists of the addition or omission of the RoboKy character, who plays more like a quicker mobile unorthodox variation of the original Ky than the clunky bomb-ejecting robot of later adaptations. The latest version, although not always welcomed by fans of the series, adds Order Sol and A.B.A. to the roster.

Guilty Gear X2 #Reload (2003): Adjustments on balance high-level play were made and Robo-Ky was made playable from the beginning. The number of challenges in Mission Mode was increased to 100, Survival Mode has 1000 levels in #Reload, and the player can damage the enemy normally or perform combos to gain next level quicker.

Guilty Gear XX Slash (2005): The game's balance was reworked by changing properties of certain moves and including new moves for some of the characters. Two new characters were introduced to the game, these being A.B.A, who debuted in Guilty Gear Isuka, and Order-Sol, who is Sol Badguy with an entirely different costume, and moveset.

Guilty Gear XX Accent Core (2006): In addition to balance changes, Accent Core features a new type of special move, the "Force Break," which uses 25% of the tension gauge. It also introduces moves that make opponents stick briefly to walls or slide across the floor of a stage. New additions also include "Slashback," a form of parrying with reduced block stun, and throw breaks. Accent Core also underwent a major aesthetic change for the series. In addition to a new opening movie, and a redesigned menu, all voices, including that of the announcer, have been re-recorded (or replaced with previously unused samples), sometimes by different actors. The playable character artwork was also redone, and new background songs were added. On the other hand, the Story Mode, as well as Justice and Kliff were removed.

Guilty Gear XX Accent Core Plus (2008): No changes to the battle system have been made, but new features were added. Features include Kliff and Justice's return, with appropriate changes and additions, the return of Mission Mode, a new Survival Mode with level-up features, a new Gallery Mode with new illustrations, and bug fixes, rebalances, and tune ups from the previous version. It also features a new Story Mode.

Guilty Gear XX Accent Core Plus R (2012): The game's balance was reworked again and in-game bosses Kliff and Justice are also balanced for regular play.