Doom Cheat Codes

To use a cheat code in most versions of the game, one simply types the code while playing (this also applies while in automap mode). On the iPhone version of the game, touch the screen with 4 fingers at any time to bring up the keyboard. After the last letter has been entered, a message of acknowledgment will appear at the top of the screen. The status bar, face, and ingame view may also change, depending on the effects of the code.

Cheat codes are disabled on the "Nightmare!" skill level, except for the iddt and idclev cheats.

Cheat codes may be different on non-QWERTY keyboards. For example, in France, idkfa may be idkfq, because of the AZERTY keyboard layout commonly used there.

All Doom engine versions
Prints the message "Doesn't suck - GM". Taylor's explanation for this message: "Choppers is a State Programming Contest game that a friend of mine named Guy Maor (GM) helped write. He's a little defensive of it 'cause it wasn't *quite* finished on the release day. Was a cool two-player Rescue Raiders rip-off. He was drunk and talked to me one night, and I thought I'd put it in."

CLEV stands for 'change level'; it could also be interpereted as "see (C) level."

Taylor and two fellow hackers made up an informal fraternity called Delta-Q-Delta (hence the DQD) during their college days. The "Q" stands for "quit", and represents the grade members should strive to receive in their classes.

According to the function P_DamageMobj in p_inter.c, "invulnerability" only protects the player from attacks doing less than 1000 points of damage. There is no form of attack in the game that does more damage than this number, except one: a telefrag, which inflicts 10000 points on the target. This is why a player in God mode can still be killed by telefragging. This also means that DeHackEd can be used to circumvent god mode by creating incredibly powerful weapons; some examples of this effect can be found in The Sky May Be.

DT stands for 'Dave Taylor'. The code can be used in cooperative multiplayer games by first pressing T and then typing the code while holding ALT.

FA stands for 'full ammo'. This cheat code is not present in versions prior to 1.666.

KFA stands for 'kick fucking ass', killer fucking arsenal or 'keys & full ammo'.

MUS stands for 'music'. Certain selections may call for invalid music lumps (see IDMUS requests invalid music). In The Ultimate Doom, idmus40 will play the same music as idmus39 (D_E3M9) and idmus41 to idmus45</tt> will play music from the intermission, main, and end screens. In Doom II, the non-level tracks are idmus33</tt> to idmus35</tt>.

MYPOS stands for 'my position'.

SPISPOPD stands for 'S'mashing 'P'umpkins 'I'nto 'S'mall 'P'iles 'O'f 'P'utrid 'D'ebris. See more in SPISPOPD article.

Doom95
The prefix FH in Doom95 cheat codes stands for the initials of Fred Hommel, the programmer who created the codes.

Here's another cheat, it works with all DOOM! notarget, first open the console by pressing the ' button and then type notarget. The result is the monsters do not see you nor hear you until they are shot (killing them hopefully). You can pick them off as you see fit unless they somehow survive during fire, this is normal.
 * 1) HALL refers to Jason Hall, CEO of Monolith, who requested that particular cheat (hence the "BY REQUEST..." message that displays when the code is executed). The actual damage done to each monster is 10,000 hit points.
 * 2) Upon typing the fhshh</tt> cheat the message "be vewy vewy quiet..." is displayed. This is a reference to Elmer Fudd's catchphrase "Be vewy vewy quiet, I'm hunting wabbits!", in the beginning of a Looney Tunes or Merrie Melodies animated short. The message "Achoo!" appears when the cheat is disabled (the joke being you sneezed, and the monsters heard you).