The concluding chapter of the Xenosaga science fiction role-playing game series begins one year after the events described in the previous episode. The main heroine Shion Uzuki is shocked by the discovery that implies a connection between Vector Corporation, the organization she is working for, and the Gnosis event, which set the whole story in motion. She leaves her post and tries to solve the mystery on her own. Meanwhile, the KOS-MOS project is halted, and a mysterious new android, T-elos, emerges to replace it. Shion and her friends are about to fight the ultimate battle that will determine the destiny of mankind.
The third episode retains the combat basics of the two previous games, resembling more the system of the first episode. Weapon and equipment management returns, and the complex break system from the second chapter has been simplified. Once again, there are two kinds of combat, in human form and piloting giant robots. The usage of ether attacks, boost gauge, and other typical Xenosaga gameplay elements are also present in this game. Robot combat is more prominently featured and is handled somewhat differently, the giant gears having a wider variety of attacks at their disposal. Both player-controlled and enemy parties have now a special bar that renders them immobile when filled. Exploiting this feature is yet another strategic addition to the combat.
There is an in-game database listing all events, people, items, monsters and locations. Next to the main storyline, there are 60 puzzle mini-games. The game includes an editor to create these custom puzzles and share them with friends.
