The Doomsday Engine is an enhanced DOOM source port for Windows, Mac OS
X, and various Unix platforms. It is based on the source code of id
Software's DOOM and Raven Software's Heretic and Hexen.

* Hardware-accelerated OpenGL graphics engine
* 3D positional audio for sound effects (not supported by all audio plugins)
* 16-player client/server networking via TCP/IP
* Graphical Control Panel for configuration, accessed quickly with Shift-Escape
* 3D models: Quake's MD2 format and Doomsday's DMD format with LOD support
* High-resolution textures (PNG, TGA, PCX) and detail textures
* Map lighting emulates the effects of radiosity for a more natual appearance
  (FakeRadio: shadows in corners)
* Smooth movement of objects, world structures and the camera.
* Colored, dynamic lighting for world surfaces, 3D models, sprites and particles
* Object shadowing effects
* Particle generators for special effects
* Decoration effects on world surfaces: light sources and particle generators
* Lens flares and glowing objects
* Support for skyboxes and 3D sky models
* EAX and A3D environmental sound processing effects
* Upsampling of sound effects

WWW: http://www.dengine.net/