Coherence

In game studies, coherence refers to the believability of a game's fiction when put out of context of its underlying rules.

Coherent elements help contruct the fiction -- plot points, character reactions, and realistic physics. Incoherent elements break the illusion of a fictional world and reveal rule-like elements -- extra lives, the ability to pause, and invisible walls. The easier it is for the player to explain the fiction without mentioning the rules, the more coherent a game is.

The term was proposed by game studies researcher Jesper Juul in Chapter 4 of his book Half Real: Video Games between Real Rules and Fictional Worlds (Juul 130). Coherent and incoherent game worlds are mentioned as two of his five major types of game worlds.