Centipede mini-game: Successfully complete the game to unlock Centipede at the "Atari Games" menu. Note: If it is not unlocked as soon as you complete the game, restart your Xbox, reload your game, and recheck the "Atari Games" menu. Missile Command mini-game: In the vet's office on level 13, walk into the small office on the far right side. Approach the computer and press A to play Missile Command. Then, successfully complete the level to unlock the game at the "Atari Games" menu.