Wiktionary
n. (context video games English) A style of game in which the player observes and controls a large-scale environment, such as a city.
Wikipedia
A god game is an artificial life game that casts the player in the position of controlling the game on a large scale, as an entity with divine and supernatural powers, as a great leader, or with no specified character (as in Spore), and places them in charge of a game setting containing autonomous characters to guard and influence.
This is not to be confused with god mode, a state found in many video games (usually afforded the player through use of a cheat or granted as an unlockable in-game reward) wherein the player-character is granted invincibility, invulnerability, or both.
God Game is the title of a science fiction novel by Rev. Andrew M. Greeley which was first published in 1986. It was published in hardcover by Warner Books with a paperback edition by Tor Books following in 1987.