[tedopon]

Takes place after humans leave earth poisoned and broken for the stars. Some don't go for various reasons: poverty, sickness, or personal choice. Thousands of years later, humans (who are basically post
apocalypse barbarians, ie "magical" red fireaxes and ox drawn UHauls)
live in a world where Nature has reasserted itself.
Natives of the planet live in ancient ruins of civilization. The world is decidedly low tech, but I've already decided that in addition to the evolved flora and fauna that rose up from the waste of human progress there will be other spooky things like heads in jars and roving tribes of slave herding cannibals. The original idea had a satellite orbiting earth with hibernating humans aboard ala Dr Who, so the many worlds concept (and all of the outside influence that comes with it) is a welcome addition.
Basically a world of cavemen and ferocious wildlife, a mostly toxic environment, and infrastructure in ruin. The natives have a well developed mythology that is an absolute distortion of all the bits and pieces of knowledge passed down over the centuries via word of mouth.
I am developing a set of supernatural mechanics for the setting. Of course, some of this is technological, some biological and some "spiritual", so right now it's basically a hodge podge of contradiction.
I'm looking forward to this project a lot.