Caverns of Darkness

Caverns of Darkness is a 12-level mapset for Doom 2 by The Chaos Crew in 2002, using a custom source port based on MBF called the "COD Engine", which runs under MS-DOS. Because of the custom engine, MS-DOS or a DOS emulator is required to play. The mapset is well known for its liberal use of faux-3d constructs using midtextures, and ambient sounds.

ZDoom Patch
In 2008, Graf Zahl released a patch for Caverns of Darkness, allowing it to be played using ZDoom. It works by substituting DECORATE actors in place of the original custom things.

Levels

 * MAP01: Surface by Christopher Lutz
 * MAP02: Six Feet Under by Christopher Lutz
 * MAP03: Hell & High Water by Christopher Lutz
 * MAP04: Hydrosfear by Nokturnus
 * MAP05: Command Control by Emil Brundage
 * MAP06: Periditions Abyss by Christopher Lutz
 * MAP07: Lava Processing by Christopher Lutz
 * MAP08: The Pit by Christopher Lutz
 * MAP09: Hellmine by Nokturnus
 * MAP10: Caverns of Darkness by Christopher Lutz
 * MAP11: Symbol of Grace by Christopher Lutz
 * MAP12: The Stand by Christopher Lutz

Trivia

 * Caverns of Darkness was planned to be ported to The Eternity Engine, but was never officially completed.
 * The COD Engine allows fake contrast to be toggled. It serves no real gameplay purpose.