Startopia
Startopia is a computer game from Mucky Foot Productions and published by Eidos, combining features from games such as Dungeon Keeper and Theme Hospital.
It is set onboard a giant space station, and requires the player to build an environment which will attract members of various alien species to the station. The game has an interesting sense of humour, similar to that of Dungeon Keeper in many ways. The player has no direct control over the characters that wander about, although the game is largely about influencing their actions in one way or another.
The hardware requirements are low by current standards (350MHz processor, 64 Mb RAM, 8 Mb 3D graphics card), the game is now in the "budget" range, and there is a demo version available.