Although it's hardly a new idea, I've been (off and on) fascinated with the concept of a prehistoric sword & sorcery setting. This isn't terribly different than the idea behind the iconic Sword & Sorcery setting, Howard's Hyborian Age or his earlier Pre-Cataclysmic Age of Kull of Atlantis. Clark Ashton Smith's Hyperborean cycle of prehistoric, temperate Greenland also fit into this mold, as do L. Sprague de Camp's Conan ripoff stories of the Pusadian Cycle. However, the primary source that really kicked off this idea in me several months ago was the mediocre movie 10,000 B.C. which takes an excellent idea, and then fails to do anything really dramatic with it.
More recently, I started reading James Silke's Death Dealer novels (I found the first three of four in a used book store for $2 each a month or so ago) which are set in the Mediterranean Basin during the Ice Age, a time which he assumes the basin was not flooded. As near as I can tell, this view is not supported by anyone anymore, and the closest thing is the Messinian Salinity Crisis some 5 odd million years ago in the late Miocene when the Mediterreanean partially (or maybe completely) dried up. Of course, this was twice as long ago as the best estimate for the appearance of Homo sapiens so naturally it doesn't work. Still; the idea of a Pleistocene high civilization that has since vanished without a trace is not a new one, and some archeological suspect, yet entertaining nonetheless books about the subject do appear from time to time. Heck; Graham Hancock seems to have built an entire career in trying to prove the existence of global high civilization that existed some 10,000 years or so ago and which subsequently disappeared and set humanity back eons to claw its way back up to where it had previously been only after thousands of years of suffering through the most prolonged dark age known to man.
I don't believe this kind of stuff for a minute, but... what if it's true? What if high civilization existed during the Pleistocene, perhaps in North America even? I started looking around for some geologically interesting places where I could construct such a setting, and came up with the idea of Lake Agassiz. This gigantic lake was once situation right in the heart of North America, and it took up more real estate than all of the Great Lakes today do combined. During the Younger Dryas, the last glacial maximum and cooling period of the Ice Age, Lake Agassiz was drained into the Atlantic Ocean. In fact, some scientists claim that it's feasible that the rapid draining of Lake Agassiz in fact caused the Younger Dryas, by putting all that cooler fresh water into the ocean and disrupting current flow. In any case, Lake Agassiz is a candidate for catastrophic, rapid draining; walls of water racing across the continental face in an event that would have been a suitable candidate for the elimination of the civilization that dwelt on its shores.
In addition to Lake Agassiz, Lake Bonneville is another good candidate; a gigantic lake that covered pretty much the entirety of what is now the state of Utah. This is another one that's believed to have flooded catastrophically about 14,500 years ago. See, this would be the difference between my setting and some of the others I've read; the utilization of real life geography as much as possible as the building blocks of the setting.
I know, I know, for anyone besides me, who cares? But I think it's an interesting challenge to try and build a setting, set around the shores of prehistoric Lake Bonneville, featuring the Pleistocene megafauna, and conforming to sword & sorcery conventions for wildness and fun.
Anyway, I'm excited. I've started making notes and playing around with maps already, and I'm eager to see what I can come up with here.