Question: What is the name of the American game designer who co-developed Dungeons & Dragons Basic Set and who developed the concept of the RPG?
Sentence (from "Dungeons &amp; Dragons Immortals Rules"): Dungeons & Dragons Immortals Rules, written by Frank Mentzer, is a boxed set for the "Dungeons & Dragons" ("D&D") fantasy role-playing game first published by TSR in 1986 as an expansion to the "Basic Set".
Relevant evidence: No