LEVEL SELECT
Hold L1+ L2 + R1 + R2 at the main menu, press Left, Circle, Triangle, Up, Square, then immediately release L1, L2, R1, and R2.

CHEATS To activate cheats, first pause game play. Press Down, L1, Up, Square. Resume game play and immediately pause the game again, then enter one of the following codes:

Air strike: Down, Up, Circle, Down, Up, Down, L1.
Cow strike: Up, Down(2), L1, Right.
Super chain gun: Left, L1, Down, Square, Triangle, Up, Down.
Thumper weapon: Down, Up, Left(2), Triangle, Up, Right, Down.
Twister weapon: Down, L1, Square, Triangle, Right, Up, X.
Grenade: Triangle, Circle, Square(2), L1, Right.
Sniper grenade: Up, Square, L1, Left, Circle, Triangle, Square.
Homing sniper grenade: Left, Up, X, Triangle, L1(2), Right.
Mortar: Left, L1, Triangle, Square, Right, Circle, Left(2).
Most interesting bomb: Down, Right, Circle(2), Left(2), Up, Square, Triangle.
Dummy decoy: X, L1, Right, Circle, X, Up, Square.
Seal: Circle, Triangle(2), L1, Right.
Bones seal: Triangle, Right, Circle, Left(2).
Super gun: Right, Up, Down, L1, Down, Circle, Left(2).
Homing bullets: Square, L1(2), Right.
World's smallest nuke: Down, Up, Square, Triangle, Down, Circle(2), Right.
Full hit points: Right, L1, Square, Triangle, L1, Down.
Faster speed: Right, Circle, Triangle, Circle, X.
Nodie: Circle, Triangle(2), Circle, Right, Up, Left, L1, Square.
Earthworm Jim power-up: Up, Down(2), L1, Right