To use a cheat code in most versions of Doom, one simply types the code while playing (this also applies while in automap mode). In the iPhone version of the game, touch the screen with four fingers at any time to bring up the keyboard. After the last letter has been entered, a message of acknowledgment will appear on the top of the screen. The status bar, face, and in-game view may also change, depending on the effects of the code. Cheat codes are disabled on the "Nightmare!" skill level, except for the idclev and iddt cheats.