The Blender Institute has just released a new project. After releasing under the
Creative Common two awesome
Pixar quality short subjects
Elephants Dream and
Big Buck Bunny, the Blender Institute is now releasing
Yo Frankie!, a fully free and open source 3D game under the Creative Common license, everything from the artwork to the code is freely re-usable and modifiable even commercially.
By running the game directly from Blender, you can even modify it and see what happens directly from the software, a nice way to learn how to do your own game.