As the name suggests, game semantics models computation as the playing of a certain kind of game, with two participants, called Player (P) and Opponent (O).
P is to be thought of as representing the system under consideration, while O represents the environment. In the case of programming languages, the system is a term (a piece of program text) and the environment is the context in which the term is used. This is the main point at which games models differ from other process models: the distinction between the actions of the system and those of its environment is made explicit from the very beginning.
Это похоже на теорию игор