To model the exchange of files, we define a 2 2 matrix where every player chooses between two actions: cooperate (C) or defeat (D). The defeat action models the behavior of users that do not share resources, but download resources from the others, and this problem is known as the Free-Riders problem or the Tragedy of Commons (Hardin, 1968). From the actions selected by both players the game tool determines the payment for each one.