Image: A kitchen in TFM
The Flight of the Maxima (TFM) is an unlikely fusion of Sci-fi, dark comedy and medieval Christianity.
It is a free roaming roleplaying computer game where you can explore vast lands, talk to an extremely diverse amount of people, and do a lot of crazy things that certainly sounded like a good idea at the time.
There's also a central story element that begins with you suddenly finding yourself a long way from home and dealing with… well let's not spoil things just yet.
The game can run on Linux and Windows, is intended to run on Mac (untested as of late), and both the games code and it's assets are Open Source (BSD), which means you can modify and redistribute the game nearly any way you want.
The game compiles fine for example on Arch Linux 64bit (with these hints). One license problem is the use of non-free FMOD but if I understand correctly, that dependency is optional.
Video: First steps in TFM 0.4