Tap the screen with 4 fingers, a black screen will come up, type in "god" hit enter, you now are in god mode and are invincible...type in "give" and hit enter, and now you get full life, ammo, and keys.
I do not like using cheat codes to play games. It really sucks. There is no excitement of playing games if you use cheat codes to qualify. I think some gamers are really going to agree with me. Is not it?