Detalion is a Polish developer of computer software games. It was closed down due to financial difficulties in March 2005 but its founders created Detalion Games and Detalion Arts (now both defunct as well) to take its place. They developed such notable adventure games as Reah: Face the Unknown; Schizm: Mysterious Journey (published as Mysterious Journey: Schizm in North America); Mysterious Journey II, and most recently, Sentinel: Descendants in Time (later renamed Realms of Illusion). These games (particularly Mysterious Journey: Schizm) were noted for the complexity and great difficulty of their puzzles, and also were hailed as having some of the best graphics in the industry at the time. Detalion was one of the first developers to use the DVD-ROM disc as an effective medium for software distribution.