If you point your browser over to here
you'll notice a great DOOM port that plays DOOM, DOOM II, Heretic, Hexen, and one other DOOM engine based game, all shareware and registered.
The engine itself is based on the Quake engine so is highly portable. I've been slowly converting in my spare time and the only part that looks like a pain is the sound (probably no music for a while). I would be doing better but i've been having issues with GCC, if I ever get it working I'll compile it and fix any errors. Some of the many benefits of this engine are:
VavoomC Scripting language - write mods for DOOM
MD2 Model support for any objects in the game
Client server architecture (includes bots)Free look
Quake style Binds
And practically everything else good about Quake.
Additional features will be (hopefully):
Compressed saves - including configuration
2/4 player split screen action (hopefully rigged so you can run 2+ DC's together for 8-16 player action)
Any help that anyone wants to contribute is welcome, not much progress yet as explained above but I don't have gobs of time or a working compiler. Not too much that needs porting really, it's good code. Almost done with graphics.