Open source clone of Theme Hospital
Space exploration and combat game
A free and highly sophisticated flight simulator
Julius is an open source re-implementation of Caesar III
Multiplayer infinite-world block sandbox game
A construction and management simulation video game that simulates amusement park management
A highly detailed transport simulation game
Physics sandbox game
Rescue Helicopter Simulator
Taigo is a virtual pet for your desktop
The Fun-Focused Free Software Voxel World Game