Also called world-oriented. Approach to gaming where the GM and players attempt to simulate a reality (not necessarily the reality, possibly a particular genre or fictional world). Considerations that cannot be expressed in terms of the game world, are disregarded. Part of the threefold model.

Simulationist GM employs a gaming style which values resolving in-game events based solely on game-world considerations, without allowing any meta-game concerns to affect the decision. Thus, a fully simulationist GM will not fudge results to save PC's or to save her plot, or even change facts unknown to the players. Such a GM may use meta-game considerations to decide meta-game issues like who is playing which character, whether to play out a conversation word for word, and so forth, but she will resolve actual in-game events based on what would "really" happen.