Beyond Dark Castle is a computer game, released for the Macintosh in 1987 by Silicon Beach Software. It was designed by Mark Pierce and programmed by Jonathan Gay. It is the sequel to Dark Castle, with more levels, monsters and items, as well as a larger game map and longer levels. A second sequel, Return To Dark Castle, was released in 2008.
Source: Wikipedia, "Beyond Dark Castle", available under the CC-BY-SA License.