Free doomsday software for linux

Doomsday Engine is a 3D-graphics enhanced game engine for Doom, Heretic, and Hexen.
The Doomsday Engine is an enhanced Doom source port, based on the source code of id Softwares Doom and Raven Softwares Heretic and Hexen.
The purpose of the project is to create versions of Doom, Heretic and Hexen that feel the same as the original games but are implemented using modern techniques such as 3D graphics and client/server networking. A lot of emphasis is placed on good-looking graphics.
Main features:
- Supports Windows, Linux/Unix, and Mac OS X operating systems.
- Hardware-accelerated 3D graphics (OpenGL and Direct3D) and sound effects (DirectSound3D).
- 16-player multiplayer over LAN or the internet.
- Dynamic lighting and shadow effects.
- 3D models and particle effects.
- Dynamic light effects and lens flares.
- Simple shadows for objects.
- Support for high-resolution textures and detail textures.
- 3D skyboxes.
- Quake-style runtime console for modifying settings and giving commands.