Intentional or not, OD&D represents a milestone in American fantasy – and maybe the last un-muddled example of the genre it inspired. Most of D&D’s thousands of imitators, in game and fiction, preserve the game’s democratic bones (cash economy, guns for hire, rags to riches stories) while overlaying a medieval-European skin. The combination is not fortunate. Gygaxian levelocracy, where a villager can rise to become a baron or a “Conan type”, is fundamentally incompatible with the European fantasy typified by Lord of the Rings, in which no fellowship can alter the fact that Sam is by birth a servant, Frodo a gentleman, Strider a king, and Gandalf a wizard.
OD&D’s American strain of fantasy didn’t even last within TSR. In 1980, Gygax himself reworked the World of Greyhawk into what looks, from its cover, like a supplement about Arthurian Knights.