Invincibility

While playing press Start and enter Square, Circle, Left, Right, Circle, Square.

Max Ammo

Press Start and enter Left, Right, Circle, Circle, Circle, Right, Left

Level Select

Save the game and return to the main menu. Select the "Resume Game" option, then highlight the previously saved game and press Up, Down, Down, Up, Left, Up, Right, Down.

Level Skip

Pause the game and press Up, Down, Left, Right, Right, Left, Circle.

Fatboy Mutator

At the title screen, press Circle, Circle, Circle, Up, Down, Down, Up, Circle, Circle, Circle. Select multi-player mode and choose the Fatboy Mutator. Get killed to have the new Mutator get thinner. Get a kill to have the Mutator get bigger