When a person performs a certain action, it signifies that he is causing a certain event to occur. Therefore the action is conveying a certain true sentence. Playing a game is a mutual activity, namely the listener and the speaker undertake an exchange through a linguistic dialogue or communicate through action. Because of the peculiar nature of the action, the actions in games belong to an activity where the speaker speaks "true words" and the listener hears "true words." A static game is a process through which the participants are simultaneously "speaking" and "listening"; and a dynamic game is a process where speaking and listening take place in turn. Each step of a dynamic game is a "speaking-listening" exchange. Through "listening" and "speaking," changes in the epistemic states of the participants occur. Of course, the degree of change depends on the type of game being played. In a dynamic game, each participant proceeds through a process of induction, and thus forms new epistemic states.