kill.switch Cheats for PlayStation 2

If you in cover and a guy is shooting at you blind fire back but don't aim for him, aim for the space around him and get back into cover, soon enough he should run up and try to kill you just smack him with the butt of your rifle for an easy kill

Complete the game, then press L1, R1, square, square.

Level Select:
In normal or hard difficulty setting successfully complete the game to unlock the option that will enable you to choose any level in the game.
Grenades:
Throw a grenade on any level when there are two enemies talking together. They will be too distracted to look and see what it was. This is useful at the begining of the Think like a gun level.

If there's a guy giving you trouble just take cover while he shoots at you.
sooner or later he'll stop and just stand there because he's out of ammo, then you can just shoot him.