- There are several actors
- Each actor can influence the state of the model by choosing one among several options
- This choice influences the state of the system, and the choices the other actors have
This definition excludes all "games" where there is only one actor. Game theory developed from describing very specific games into a model that is used for strategic decision-making. John von Neumann and Oskar Morgenstern first described game theory. Other people known for their work in game theory include Émile Borel.