When something reminds me of Icehouse, I post it: Triptych is a puzzle game for Windows, Mac, and Linux in which you drop groups of three colored blocks, and when three of the same color touch each other they disappear. The trick is that this happens with real physics – blocks bounce off each other with all the Newtonian might your CPU can muster, and things get non-Cartesian pretty quickly. Check out the screenshots if you don’t believe me. This is all coming from the people who made that game where you build a bridge, then drive a big train over it and see if it breaks. Yes, folks, Calvin and Hobbes is slowly becoming reality. Both games are inexpensive and recommended.