Nosgoth was a free-to-play multiplayer action game, developed by Psyonix and published by Square Enix for Microsoft Windows through digital distribution. It was a spin-off from the Legacy of Kain series of action-adventure games, and took place in its eponymous fictional universe. Nosgoth employed a player versus player system in which each match consisted of two rounds. Teams were composed of characters assigned to one of two races: vampires, designed around hack and slash combat; and humans, whose gameplay was styled after third-person shooters. Between rounds, teams would switch to control the opposing race, and the team which accumulated the most points by fighting their counterparts won the match.

Initially announced in June 2013 following internet leaks, Nosgoth was the first Legacy of Kain-associated game to debut in almost ten years, preceded by 2003's Legacy of Kain: Defiance. Though once intended for release as part of a single-player project, Legacy of Kain: Dead Sun, it was reconceptualized and continued development as a standalone title following Dead Sun's cancellation. When officially revealed in September 2013, Nosgoth attracted negative reception for its conceptual departure from the traditional single-player and story-driven Legacy of Kain formula. Initially beginning its closed alpha and opening up its servers to registered players in late 2013, the game's open beta began in January 2015 and ended in May 2016.

On April 8, 2016, Square Enix Europe announced that Nosgoth's servers would shut down on May 31, 2016. Nosgoth's official forums also shut down on June 14, 2016.