Gauntlet: The Deeper Dungeons is an expansion pack for the original ports of Gauntlet with 512 new levels and required the original program. It was released in 1987 by the British company U.S. Gold in the UK and Europe, and Mindscape in the USA. It was released for Amstrad CPC, Atari ST, Atari 8-bit, Commodore 64 and ZX Spectrum. It was developed by Gremlin Graphics Software Ltd.
Many of its levels were entries in a competition throughout Europe in which only ten winners were awarded prizes, "A Gauntlet T-Shirt and a copy of the program for their computers." The contest was announced in the instructions of many of the ported games: "In early 1987, U.S. Gold will release an expansion cassette for Gauntlet containing hundreds of new levels and treasure rooms. You can have the chance to have your own maze included on this tape!" The levels are presented randomly and its artwork is the side panel artwork of the arcade cabinet with only the main characters shown. The enemies were removed from the image and replaced with a pink background.
Source: Wikipedia, "Gauntlet: The Deeper Dungeons," available under the CC-BY-SA License.