Enter the following as Passwords at the Vault Screen:

Extra Life: Triangle, Circle, Star, Square, Square, X.

Ten Lives: Square, X, Circle, Circle, Triangle, Square.

Invincibility: Square, Star, Triangle, Square, Triangle, Diamond.

Play as Alfred: Square, X, Triangle, Square, Star, Star.

Play as Cuz: Square, Diamond, Square, Square, Triangle, Diamond.

Play as Rex: Square, Star, Star, Square, Triangle, Triangle.

View FMV Sequence: Circle, Triangle, Square, Star, Diamond, Star.

View FMV Sequence 2: Diamond, Star, Square, X, Triangle, Circle.

Invincibility:
Pause the game, hold L2 and press Down, Up, Left, Left, Triangle, Right, Down. Gex should now be invincible.

Gex quotes:
Pause the game, hold L2 and press Down, Right, Left, Circle, Up, Right. Unpause and press Select to hear a witty Gex line.

GameShark Codes

Invinciblility800b37b80005