The arena can be played at any time once you have unlocked that level during the game. Once in the arena, you can choose to play two game modes: Time Trial or Body Count. Time Trial mode asks you to kill a certain number of enemies in increasingly shorter times. Body Count mode asks you to defeat a certain number of enemies in time limit. Both of these modes have a set of challenges like the Baumusu Challenges, called Arena Challenges - also viewable from the start menu during game play. If you complete the Arena Challenges in the given time limits for both modes, you can unlock special content for the game. Time Trial Arena Challenges unlock special artwork and Body Count challenges unlock costumes that Rau can were during the game. If you have acquired all of the Tuku's, you can use all of your weapons on any arena level.