Unlock One Life Mode:
Beat the game on Hard difficulty.

Unlock All Single and Multi-player Levels:
Enter the following code at the Extras screen.
Down, Right, Down, Right, Up, Down, Up, Left

Paintballs Mode:
Enter the following code on the Extras Screen.
Right, Left, Right, Left, Down, Down, Up, Up

Unlock all Skins in Multiplayer:
Down, Left, Up, Left, Right, Down, Left, Up


Enter the following cheats during game-play after you have paused the game

Full Eye Power:
L1, R1, L1, L2, L2, R2, R1, L2

Full Health and Armor:
R1, R1, R2, L2, R2, R1, L1, R2

Unlock Eye Powers:
L1, L1, R2, R2, R1, R2, L1, L2