Overview: This program sets up a two-player, multi-decision matrix game with symmetric payoffs. The payoff symmetry makes it easier to set up a large matrix game, since you only need to enter half as many payoffs. The symmetry permits a simplification of the instructions, since there is no distinction between row and column roles. A more general program that allows payoff asymmetries is listed as the MGN game under the Games Menu. With large numbers of decisions, it is convenient to use some standard payoff formulas that permit linear, quadratic, and min/max structures. For example, payoffs can be set to correspond to matrix-game versions of Cournot or Minimum-effort Coordination Games; these two games are implemented by the default setup parameters.