FreeDM

FreeDM is a fast-paced competitive deathmatch game, part of the Freedoom project.

Rather than the usual single-player focused levels, these contain no monsters and

are intended for deathmatch only. It is compatible with mods for Doom II.

There is a massive back catalog, spanning over two decades, containing

thousands of Doom levels and other modifications (“mods”) made by fans

of the original Doom game. Freedoom aims to be compatible with these and

allows most to be played without the original Doom datafiles.

Freedoom: Phase 1 aims for compatibility with The Ultimate Doom,

also known as plain Doom or Doom 1.