PrBoom is a modified version of ID Software's classic game Doom.  It
runs on several platforms (including Win32 and Unixes) and features
many additions to the original game.  It also supports multiplayer
games.

You will need an IWAD for PrBoom to be fully functional.  An IWAD is
the main data file containing the graphics and levels for Doom.  If
you have a copy of one of the original Doom games, simply copy your
Doom, Doom 2, Ultimate Doom, or Final Doom IWAD (doom.wad, doom2.wad,
tnt.wad, and plutonia.wad respectively) to ${PREFIX}/share/prboom/.
If you do not possess any of those, you can use the shareware IWAD
which is available at:

ftp://ftp.idsoftware.com/idstuff/doom/doom-1.8.wad.gz

Install it to ${PREFIX}/share/prboom as "doom.wad".

If you wish to be able to play the Doom background music, simply
install any FLAVOR of the audio/timidity port.