FlightGear Flight Simulator: free open-source multiplatform flight sim
WW2 U-boat simulation
BattleTech MUX Client
3D Multiplayer Hover Soccer
3D space trading and combat game
A planetarium software that shows a 3D simulation of the night sky
Open-DIS implements the IEEE DIS protocol in multiple languages.
Sorry this project is no longer being supported
A railway signalling simulation game