Return To Dark Castle is a 2008 platform game for the Macintosh. It is the third game in the Dark Castle series, following the original Dark Castle (1986) and its sequel Beyond Dark Castle (1987), and the first to be developed by Z Sculpt. Development on the game, begun in 1996, was notoriously protracted, and the game was often labeled vaporware. Return To Dark Castle was originally scheduled to be released in Winter 2000, but was not released until March 14, 2008.
The player fights his way through various areas, inside and around the Dark Castle, in an attempt to defeat the Black Knight. The player's character, named Bryant by default, is the nephew of Duncan, the protagonist of the earlier Dark Castle games. In the game's intro, we learn that Duncan never returned from his quest to the Dark Castle. Bryant now approaches the castle in an attempt to succeed where Duncan had apparently failed. Bryant must collect 10 orbs hidden around the castle (similar to the orbs from Beyond Dark Castle) before he can confront the Black Knight.
Source: Wikipedia, "Return To Dark Castle", available under the CC-BY-SA License.