H-Craft Championship is a futuristic racer that's free and open source, and the developers kindly let us know about a new version.
The developers mentioned this about the new version:
QuoteIt's a free Sci-Fi racing game which runs on GNU/Linux. Version 1.3 comes with new controls and also fixed a few crashes caused by sound which we had on Linux 64 bit systems. No restrictions or demo versions - the game is just free :-)
You can find the source code here. They state most of it is under the zlib-license.
If you try it out, come back and let us know how it runs for you.