What’s your favorite take on Atlantis as it pertains to gaming—Aliens? Mer-people? Exceptionally ancient Greeks?
I liked the ideas in Randall Garrett’s Gandalara Cycle. A quick gloss is that there’s a civilization of near-humans that live in a desert… at the bottom of the future Mediterranean Sea. They’re adapted to the thicker atmosphere (since they’re below sea level) and they can’t (easily) get out & take over Africa and Europe. He created a pretty good analogue culture– close enough to human to be very identifiable, with a few sci-fi/fantasy elements. Their culture wasn’t much stranger than most foreign cultures appear today- easy enough for most role-players to adapt to.