Successfully complete single player mode on the easy difficulty setting to unlock four costumes for Batuo and Motoko (in game and multi-player); infinite grenades and small gun ammunition (in game); the Rice Dome multi-player map; and yellow menus.
Successfully complete single player mode on the hard difficulty setting to unlock three bonus costumes for Tachikima.
Successfully complete single player mode without using a continue to unlock infinite ammunition for the grenade launcher, sniper rifle, rocket launcher, and the automatic rocket launcher.
Successfully complete multi-player mode on the easy difficulty setting to unlock Batuo and Motoko as playable characters; three bonus costumes for Batuo and Motoko; and the Dome level.
Successfully complete multi-player mode on the normal difficulty setting to unlock the Arm Suit and AI Tank as playable characters.
Successfully complete multi-player mode on the hard difficulty setting to unlock Tachikoma as a playable character.
Successfully complete the game with all the fans to unlock Motoko's fast automatic rocket launcher; infinite ammunition for the rocket launcher; Batuo's explosive laser gun; and infinite ammunition for the laser gun.
Successfully complete a stage on the hard difficulty setting without using the infinite ammunition option or choosing a weapon. If your score penalties were low and your total score high, the very hard difficulty setting will be unlocked. Do the same under that setting to unlock the next difficulty. The order is: very hard, aggressive, dangerous, execution, hopeless, nightmare, and champion.
The North American version of the game's case cover is reversible. Take it out of the case and look at the other side to see an alternate cover.
Hold R1, then press R2.