Simulation in RPGs is the aim to approximate situations, creatures, or actions in a realistic-seeming manner, as a primary focus or virtue of an RPG.
Simulation, simulationist, or simulationism refers to games or play styles that focus on rules that produce consequences that approximate observed reality. Rules of the game generally result in events or consequences that could occur in observed reality, or reality given some modification, like magic.
Simulationism is often contrasted with narrativism and gamism. There are three significant RPG theory models that deal with the relationship between and application of these terms: the Threefold Model, GNS Theory, and The Big Model.