zdoom (an enhanced port of the official DOOM source code)

ZDoom is a family of enhanced ports of the Doom engine to modern
operating systems. It runs on Windows, Linux, and OS X, and adds
new features not found in the games as originally published by id
Software. It supports Doom, Doom II, Heretic, Hexen, Strife, and more.

zdoom is only a game engine. To actually play the game, you'll need the
game data (IWAD file) from one or more of the supported games. These
include Doom, Ultimate Doom, Final Doom, FreeDoom, Heretic, Hexen,
and Strife. Place the .wad file(s) in /usr/share/games/doom.

If you don't own any of the supported games, you can install one or more
of these slackbuilds.org packages to get a playable game:

- freedoom
- doom_shareware_data
- heretic_shareware_data
- hexen_demo_data
- chexquest3

Optional compile time dependency: openal-soft, used for audio playback
(as an alternative to fmodapi, which is always built in). It will
be autodetected at build time. If you want to build zdoom without
openal-soft, set OPENAL=no in the script's environment. There have
been reports that various mods work better with OpenAL, while others
crash or misbehave; YMMV.

Optional runtime dependencies: fluid-soundfont, and/or TiMidity++ and 
eawpats (used for MIDI playback). MIDI playback is still possible when
none of these are present, just select 'OPL Synth Emulation' from the 
Options -> Sound Options -> MIDI Device menu within the game.
