This article presents a critical view of the concept of rules in game studies on the basis of a case study of role-playing across media. Role-playing in its traditional form is a complex activity including a game system and a number of communicative conventions where one player takes the role of the game manager in order to implement the rules and provide a world for the other players. In online role-playing games, a programmed system simulates the rule system as well as part of the game manager’s tasks, while the rest of the activity is up to the players to define. Some aspects may translate more or less unproblematically across media, others are transformed by the introduction of the programmed system. This reveals some important perspectives on the sort of rules that can be simulated in a programmed system and what this means to the concept of rules in game studies.