Doom · PC · 1993 · Cheat Code
Effect: Makes the player invulnerable to all damage for the rest of the level.
IDDQD — one of the most famous cheat codes in PC gaming history — was built into id Software's Doom from launch as a convenience for players who wanted to explore the game's levels without the pressure of combat. The prefix "ID" stood for id Software, while "DQD" was an internal joke among the development team. Typing the code displays the message "Degreelessness Mode On," a reference to a phrase from a sci-fi novel. God Mode became a staple of PC gaming culture and a shorthand term for invincibility far beyond Doom itself.