This program sets up a two-player, two-stage game in which one player moves first and the other follows. It is possible to control the information that the second mover has about the other player's prior decision. In particular, the first-mover's decisions are partitioned into information sets, with the number of second-mover decisions varying from one information set to another.
For a discussion of payoff factors that may generate intuitive deviations from such predictions, see Goeree and Holt (2001) "Ten Little Treasures of Game Theory and Ten Intuitive Contradictions," American Economic Review December 2001 (91) pp.1402-1422. The default settings implement a pair of games from that paper.