I tried to run this with racket and #lang scheme (as well as #lang racket) but didn’t get it to work (though I didn’t try for very long), perhaps because of backward compatibility issues. This is a bit unfortunate because it makes it harder for people interested in this topic to profit from the results and submitted programs of this tournament. Maybe you or Alex could write a brief description of how one could get the program tournament to run?
Edit: I think after posting this, I did manage to get it to work (though I don’t remember how).
Caspar Oesterheld comments on Prisoner’s dilemma tournament results