of Chaos owe no particular debt to Carr's Caverns of Quasqueton, though much of Carr's enlightening text about the art of dungeon mastering was effectively paraphrased in Gygax's version. [...] Because Keep on the Borderlands would ship with the Moldvay Basic Set, at the height of the D&D boom in 1981, it became one of the most widely known modules in D&D history, selling 750,000 copies a year. It might never have served as the gateway to adventure for so many players if it hadn't been for a certain legal dispute and its consequences". Later versions and reprints The 10th Anniversary Dungeons & Dragons Collector's Set boxed set published by TSR in 1984 included the rulebooks from the Basic, Expert, and Companion sets; modules AC2 Combat Shield and Mini-adventure, AC3 The Kidnapping of Princess Arelina, B1 In Search of the Unknown, The Keep on the Borderlands, and M1 Blizzard Pass; Player Character Record Sheets; and dice. The set was limited to a thousand copies, and was sold by mail and at GenCon 17. The Keep on the Borderlands went out of print in the mid 1980s. However, the module was partially reprinted in the supermodule compilation B1–9 In Search of Adventure (1985), which included the Caves of Chaos but not the keep or surrounding wilderness. A reprinting of the original adventure was made available in the Dungeons & Dragons Silver Anniversary Collector's Edition boxed set in 1999 to celebrate the 25th anniversary of the Dungeons & Dragons game, with slight modifications to make it distinguishable from the original (for collecting purposes). A sequel was released in 1999, Return to the Keep on the Borderlands for 2nd edition AD&D. The original B2 publication was generic in terms of setting, while the 1999 Return module placed the Keep in Yeomanry, making it a canonical location in the World of Greyhawk. The placement of the Keep in Greyhawk did not match many details in the sequel, such as several non-Greyhawk deities, nations, and peoples. At least two of the non-player character descriptions refer to details from the Mystara setting rather than Greyhawk. In 2001, Wizards of the Coast published Keep on the Borderlands, a novelization by Ru Emerson for the Greyhawk Classics series. The novel was also set in the World of Greyhawk with scant references to its location. A hacked version of the module was published for the HackMaster RPG in 2005,