At the cheat screen, enter circle, circle, triangle, square, X, triangle, triangle, square.

Unlimited Ammo: X,Tri,Tri,Tri,X,O,X,Sq
Invincability: Sq,Sq,X,Tri,X,O,X,O
All Future Weapons: X,X,X,Tri,O,O,Sq,X
All Past Weapons: O,O,Tri,Sq,X,Tri,Tri,Sq

Note: Every time you play you have to re-enter all the cheats.But Now there is no possible way you can lose so play at your speed and listen to some SlipKnot.

On the cheats menu type in:

Square,square,X,triangle,X,circle,X,circle.