Shadow Hearts[d] is a series of role-playing video games, consisting of a trilogy of titles for the PlayStation 2 (PS2) and their predecessor Koudelka for the PlayStation. The entire series was developed by Sacnoth (later Nautilus); Koudelka was published by SNK in 1999, while the Shadow Hearts trilogy were published by Aruze from 2001 to 2005. Multiple other publishers handled the titles overseas. The Shadow Hearts chronology extends from the late 1890s to the 1920s, following different casts of characters caught in supernatural mysteries. The setting combines alternate history and cosmic horror, with real-world figures making appearances, and each title has multiple endings.
Production of Koudelka began with the formation of Sacnoth in 1997 by Hiroki Kikuta and a number of other former Square staff. Internal conflict between Kikuta and the developers eventually led to Kikuta resigning, with planned sequels to Koudelka being cancelled. The setting was instead used by Matsuzo Machida for the original Shadow Hearts. While Machida planned to continue the series after 2005’s Shadow Hearts: From the New World, these plans never materialized, with Sacnoth being absorbed into Aruze and ceasing game production in 2007.
The series saw limited media expansions, with Koudelka in particular receiving both a novelization and a manga continuation based on the initial story plan. While Koudelka saw mixed reactions from critics, the Shadow Hearts trilogy saw both contemporary and retrospective praise and is Sacnoth’s best-known product. Shadow Hearts: Covenant in particular has been praised as one of the PS2’s best RPGs, and was a commercial success for its publishers.