XiStrat (aka 'Extended Strategy') is in particular about turn-based, networked multiplayer, non-cooperative, zero-sum, abstract strategy board games (e.g., Chess, Go, Reversi variants, etc.) on 3D-visualized polyhedra and contains a server, client GUI, autoplayer engine, utilities, and documentation. Related recreational modern mathematics (single agent, cellular automata, graph/group/complexity/knot theory, discrete geometry, algebra, combinatorics, and mathematical physics) is also dealt with.
ski is a game in which you ski down an infinite slope, facing such hazards as trees, ice, bare ground, and the man-eating Yeti. Since you have put your jet-powered skis on backwards, you can't see ahead where you are going; only behind where you have been. However, you can turn to either side, jump or hop through the air, teleport through hyperspace, launch nuclear ICBMs, and cast spells to call the Fire Demon. And since the hazards occur in patches, you can skillfully outmaneuver them. A fun and very silly game that proves you don't need fancy graphical user interfaces to have a good time.