Cool idea. I once had a concept for a campaign based loosely on C.S. Friedman's Coldfire trilogy, i.e. a fantasy campaign whose underlying premise was actually sci-fi. I came up with some variant background ideas for the standard PHB races, but to get them you have to get the campaign's background premise: thousands of years ago mankind sent huge computer-controlled colony ships into space whose mission it was to travel to certain stars at sublight speeds and check to see if the planets around those stars were habitable. If so, the ships were to wake up the colonists from hibernation and then they'd take over the colonization process. All that is Friedman's premise from Coldfire. What I did myself was explain why gnomes, halflings, half-orcs, and dwarves were on that colony ship. The answer was simple: genetic engineering.
Twidgets are gnome-like humans adapted to working in space stations and bred to be scientists. They consume less food than full-sized humans and have keen analytical minds.
Slicks are halfing-like humans bred to pilot starships, and likewise to live and work in space and consume less oxygen and food. Because they are pilots they have genetically modified reflexes (i.e., the halfling's +2 Dex).
Squats are dwarf-like humans genetically engineered to withstand habitable but heavier-than-Earth gravity environments if neccessary. They were intended to be builders and engineers who paved the way for other colonists to survive in harsher environments.
Collies are humans, and the nickname is a derivitive of "colonists." These are the majority of the sleepers on the ships, and the majority who build and inhabit the new colonies.
Brutes are half-orc-like humans genetically modified for warfare or heavy labor, as required.
I made elves the alien natives of the planet. I thought I was rather clever converting the whole idea to D&D.