Recently I made a game system using Pygame. It is not a game in itself; rather it creates games based on images that it is shown. You draw a picture of the game you want to play, and in reply it will give you the game you really drew.
The software was originally written for an exhibit at Te Tuhi Centre for the Arts in Manukau City, New Zealand, from which it borrowed its name. That show ended on 10 February 2008, whereupon I released it under the GPL. Large parts of it are written in C, but the python bits are hackable without too much knowledge of that. The project's home page is http://halo.gen.nz/tetuhi/code.html, the git repository http://savannah.nongnu.org/git/?group=tetuhi, and the mailing list http://lists.nongnu.org/mailman/listinfo/tetuhi-vgs. There are plans afoot to adapt it for the OLPC XO, among other things. Douglas