MobLab’s Matrix games allows you to specify the payoff matrix for a two-player normal-form (i.e., simultaneous-move) game. Each player can have from two to four actions, and the number of row actions need not be the same as the number of column actions. The game can thus be used to represent a wide variety of two-player interactions by simply modifying the payoff structure.
Players are paired, with one the Row player and the other the Column player. If you specify multiple rounds, both pairs and player roles are fixed. Each round, after each player makes her choice, outcomes are revealed and players moves to the next round.