Celestia is an open source program for exploring space. It isn't exactly a game, since there's no particular objective; you just zoom around and look at stuff and maybe learn something about astronomy in the process. You can travel to other galaxies, but it's based on real astronomical data so our own solar system is far more detailed than anything else out there. I'd been playing with it for a while, but I just realized how much better it looks with some of the alternate textures available from the Celestia Motherlode.
Submitted by nickaubert on 2009, August 25 - 22:49