Chapter 4 Repeated games with complete information The theory of repeated games is concerned with the analysis of behavior in long term interactions as opposed to one shot situations; in this framework new objects occur in the form of threats cooperative plans signals etc. that are deeply related to “real life” phenomena like altruism reputation or cooperation. More precisely repeated games with complete information also called supergames describe situations where a play corresponds to a sequence of plays of the same stage game and where the payoffs are some long run average of the stage payoffs. Note that unlike general repeated games [see for example Mertens Sorin and Zamir (1992) ] the stage game is the same (the state is constant; compare with stochastic games; see the chapter on ‘stochastic games’ in a forthcoming volume of this Handbook) and known to the players (the state is certain; compare with games of incomplete information Chapters 5 and 6 in this Handbook).