dhewm 3 is a Doom 3 GPL source port, know to work on at least Windows, Linux, Mac OS X and FreeBSD. The goal of dhewm 3 is bring DOOM 3 with the help of SDL to all suitable platforms. Bugs present in the original DOOM 3 will be fixed (when identified) without altering the original gameplay. WWW: https://github.com/dhewm/dhewm3