DOOM Retro is the classic, refined DOOM source port. It represents
what DOOM should be today, in all its dark, gritty, unapologetically
pixellated glory.  DOOM Retro's source code is forked from Chocolate
DOOM, with enhancements from other DOOM source ports, as well as many
orignal ideas. DOOM Retro is deliberately minimalist by design, and
does a few things differently when compared with other source ports.

The game looks in /usr/share/games/doom (and a few other places) for
game date. To play Shareware Doom, install doom_shareware_data. To
play Doom 2 or the full version of Doom, copy doom2.wad or doom.wad
from the game CD or install directory to /usr/share/games/doom.

For MIDI playback, first build and install FluidSynth, then build
and install SDL2_mixer (so that it has FluidSynth support), and then
build and install DOOM Retro. Then, before starting DOOM Retro, set
the SDL_SOUNDFONTS environment variable to the path to a soundfont in
sf2 format:

i.e.

  export SDL_SOUNDFONTS=/path/to/soundfonts.sf2

Settings are stored in $HOME/.config/doomretro. After starting Doom
Retro for the first time, you will find an editable doomretro.cfg
there.