Sprite editing cheat

Sprite editing can be used as a multiplayer cheat in order to gain an unfair advantage over other players. Changes can be made to the IWAD (or a PWAD loaded) in ways which allow a means of locating the opponent not normally available in Doom, or make other changes which make the cheating player's game easier.

Detection of the use of this cheat involves visual observation of the player's screen as the game is played.

Source

 * This writeup includes text from Sprite editing Doom2 cheat, used with permission.