A planetarium software that shows a 3D simulation of the night sky
Stellarium renders 3D photo-realistic skies in real time with OpenGL. It displays stars, constellations, planets, nebulae and others things like ground, landscape, atmosphere, etc.
OpenTTD is an open source clone of the Microprose game "Transport Tycoon Deluxe". For more recent versions visit our website: http://www.openttd.org
That project is inteded to be a great FreePascal (initialy, then Mono) 3D opensource game which will do a nice flightsim game. Is is intended to work on any Unix/Windows OS-es with OpenGL/SDL.
Java version of Stellarium.