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.

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.
