i wrote about the same subject. i was subsequently answered: they'll(game company and cheat finders) probably have the cheats a week after the game is sold. besides, most fps have god and ammo cheats anyway.
Then during a single-player game, press ~ for the console and type any of the following "Codes": Code Effect
dog God Mode
fullheal Full Health
wuss All Weapons and Ammo
noclip No Clipping
notarget Show Game Version