Invincibility:
Pause the game, then press L1, L1, L2, L2, R1,
R1, R2, R2. Note: This code may need to be re-enabled after an auto-save.
All weapons and full ammunition:
Pause the game, then press L1, L2,
R1, R2, Triangle, Circle, X, Square.
Level select:
First complete the Subway level. Press Select to return
to the main menu and press Up, Down, Left, Right, Up, Left, Down, Circle.
8 pain killers:
Press Start to pause, then press L1, L2, R1, R2,
Triangle, Circle, X, Square.
(supplied by: sublime750)
Infinite ammo:
Pause the game, then press L1, L2, R1, R2, Triangle,
Square, X, Circle.
Infinite bullet time:
Pause the game, then press L1, L2, R1, R2,
Triangle, X, X, Triangle.
Slow-mo sounds :
Pause the game, then press L1, L2, R1, R2, Triangle,
Square, X, Circle.
Hint:
Durng the level with the elavator and the lasers. If you go
inside the elevator, pull your sniper rifle, look up and snipe the lazers you can ride the elevator to the top with no problem.