Unlock God Mode, ALL weapons and Unlimited Ammo

Try entering these cheats if you're struggling with the game.

Unlock God Mode:
Press L1 + R1 + L2 + R2 + Select + Start.

Unlock ALL Weapons:
Press L1 + R1 + L2 + R2 + Select + Start.

Unlock Unlimited Ammo:
Press L1 + R1 + L2 + R2 + Select + Start.

Unlock Crushing Difficulty Setting

This is the most difficult setting in the game and is unlocked by completing the 'Hard' difficulty setting in ALL 22 chapters of the game (this must be accomplished without changing to a lower difficulty on any of the chapters). When you have completed this task start a 'New Game' and the option for the 'Crushing' difficulty setting will be available for selection.