god mode

Meanings

1. A game mode where the player character is invulnerable to damage, typically activated by entering a cheat code.
2. A mode of play in (mostly) roguelike games, allowing the player to create objects on demand, to be resurrected in the case of death, etc.
3. A temporary state of extreme skill (in a sport, video game, etc.).

Etymology

In the sense "a game mode where the player character is invulnerable to damage", attested at least since 1990, as a cheat code activation message in the game Commander Keen: Marooned on Mars ("God mode enabled").