Deathkings of the Dark Citadel is an official expansion pack that was released for Hexen on September 3, 1996. It features three more hubs with a total of 20 new single player levels and six new deathmatch levels. Unlike the Shadow of the Serpent Riders expansion pack for Heretic, it had to be purchased in retail stores or by mail order. This was unusual at the time, as most non-free expansion packs also included other new or revised gameplay elements. Deathkings of the Dark Citadel, unlike Shadow of the Serpent Riders, was not packaged with the original game, meaning that both had to be purchased separately, and the expansion would not work without already having Hexen. This expansion pack also did not initially include nor enable any music. Music could be fully enabled by applying a patch specially released to address this issue (usually found online under the name "dkpatch"). Each of the hubs (The Blight, The Constable's Gate, and The Nave) features one secret level, and new puzzles based on the quest items from the original game (no new quest artifacts were added). Any type of enemy may spawn on the map. The final level of the expansion, the Dark Citadel itself, is an arena-like level, which features teleporting waves of monsters and three bosses (Fighter, Cleric, and Mage clones).