Successfully complete the game and create a cleared save game when prompted. Load the cleared saved data to begin the game at the Save Plate in the Elza. New dungeons and events will be unlocked. To fight the hidden Phobos Rigas Boss, use the UMN to go to the restricted area on the Dammurung where KOS-MOS's ship was previously located.
Bonus features:
Have a saved game from Xenosaga: Episode 1 or Xenosaga 1: Reloaded to unlock KOS-MOS' and Ziggy's swimsuits when starting a new game. Additionally, you will be given more skills points depending on your character levels in the original game's saved game file. Have a completed saved game from Xenosaga Freaks to unlock The Doctor's (Hakase) special sub-event.
Hint: Hangover Drink GS combination:
The correct combination for the Hangover Drink GS campaign is: 3-2-2.
Hint: Industrial factory puzzle:
The correct combination of blocks to shoot in the puzzle at the end of the secret industrial factory level, is: blue, gray, yellow, orange, red.