Chocolate Doom is a portable branch of the classic doom.exe experience
from the days of DOS. The author, Simon Howard, has worked to insure 
Chocolate Doom, which is nothing more than a directly modified version
of the released iD Software source code, has zero changes that affect
gameplay, look, or feel, and also re-created a DOS-like setup program to
configure the game much like the original setup.exe.

Chocolate Doom provides:
  chocolate-doom   - the game
  chocolate-setup  - the game setup program 
  chocolate-server - server for up to 4-player net games

Due to the port re-implementing the original game as closely as
possible, all original game PWADs and demos work flawlessly. Other
original features include a PC-speaker driver written with OpenBSD in
mind, just like the DOS PC-speaker driver, and a working -left and
-right network command parameter system for the 'surround display' setup
that was obtainable with the original DOS executables over an IPX
network.

Check the chocolate-*(6) manpages for additional information.