Cloak of Darkness is a text adventure game that was created by Roger Firth as a sort of testing game for various interactive fiction engines and toolkits. Because of that, it is very short and has been ported to various platforms, including IBM PCs and the ZX Spectrum. The game starts you off in an empty and dark opera house. The titular Cloak of Darkness is present inside this opera house, but its location isn't specified. The conditions on winning the game depend on how much you fumble about in the opera house.
In this run, CloakTheLurker plays a version of the game that uses "The Quill" engine and finds a note that tells him he won in record time.