Claim Stake: Asteroid Mining Game
Into Space: Hyperlink game with the author's opinions on how we should be developing space...
Java SolarPop: Solar System Demographics of the Next Millennium
MARS: Mars base simulation game from French chapter of Mars Society. Freeware for Windows.
Moon Tycoon: Build and manage a 3D lunar colony - sim game with a range of industries and strategies.
Space Colony: Sims-style game to develop a space colony. Doesn't look terribly realistic, but cute...
SpaceColonyH: A psychologically-based, problem-solving leadership game set in a space colony.