3DGE is a source port, originally based off EDGE and DOSDoom. Some commercial games have been developed specifically for it. It has added many additional features, including slopes, uncapped fps and OpenGL. The source code is maintained by Corynne and Alex Nessemman.
Windows: 98, ME, NT, 2000, XP, Vista, 7, or 8 Mac OS: Mac OS X 10.4 Tiger or above; PowerPC or Intel Mac Linux: Kernel 2.6 series and above Processor: Pentium 4 or better