Pause the game, then hold L1 and press Left, Down, Left, Down, Right, Up, Right, Up. If you entered the code correctly, a message will appear. Repeat the code to disable its effect.
Game Shark Codes
Master Code (Must Be On) 0E3C7DF2 1853E59EEEAC8B52 BCC5308A
All Weapons CE6171C6 BCA99B84
Infinite Ammo CE6171CE BCA99B84
Invincible CE6171D6 BCA99B84
Invisible CE6171DE BCA99B84
Big Heads CE6171EE BCA99B84
Title Screen Target Mini-Game CE6171F6 BCA99B84
Extra Level Under Cheats Menu CE6170FE BCA99B84
Unlock All Levels [Note] CE6171E6 BCA99B84
Note: Load a previously saved game and all levels will appear under the level select menu.