Published by Wizards of the Coast.
Released in 1981, Castle Amber is part of what I call Tom Moldvay’s “Pulp Fantasy Trilogy,” consisting of this module, The Isle of Dread, and The Lost City. I’m not sure that the term is original to me; I might have picked it up from the incomparable Philotomy Jurament. In any case, all three of these modules are homages to the pulp fantasy stories that inspired D&D, but Castle Amber is the only one that makes explicit reference to its inspiration, the Averoigne stories of Clark Ashton Smith.
Read the Full Retrospective/Review at Grognardia.