Qfusion is a game engine which is available for download and modification under the terms of GNU GPL. Recent versions of the engine extend the base Q3 rendering scheme to include per pixel shading support, soft shadows, other newer generation feature
You can download file releases of l33t project from List of release files
System Requirements
Operating System: All 32-bit MS Windows (95/98/NT/2000/XP), OS Portable (Source code to work with many OS platforms), POSIX (Linux,BSD,Solaris etc..), Linux