Dungeons & Dragons was firmly rooted in the Barsoom stories of Edgar Rice Burroughs and to a lesser extent, other sword & planet stories. There actually was a game from TSR released during the OD&D era called Warriors of Mars, which was something between a miniatures game and an RPG, but that apparently ran into legal trouble and was pulled from the market.
So sword & planet was mostly ignored (save a few Dragon articles) until Dark Sun came out, a fairly popular setting at least until TSR went under. Unofficially there have been a few attempts to make D&D with the genre. A bootleg version of TSR's Warriors of Mars using more D&Disms by "Doc", an OSR version of Swords of Almuric (based on Robert Howard's novel of the same name), and an appendix in my retro clone. But the most ambitious is these is Warriors of the Red Planet by Al Krombach with Thomas Dennmark doing illustration and layout. It released a while ago on Lulu, but now is out in PDF form, both there and RPGNow/DTRPG/OBS.
