My LotFP game takes place on Adlivun, AKA Pluto, billions of years in the future when the sun has become a red giant and teeters on the brink of collapse.
Demi-humans are allowed. Halflings were the first race of bio-engineered humans, designed for living and working in space, the asteroid belt, etc. There, their small size, superior dexterity and balance, resistance to adverse conditions, and temperament made them ideal.
Dwarves came later, and were designed for establishing colonies on inhospitable worlds such as Mercury, the moons of Jupiter, and Pluto, as well as mining. Moreso than by their physical characteristics, dwarves were defined by their psychological drive to serve. Their decline as a species came when most "old-style humans" transcended their bodies, the speed of light, and other such limitations, and left the solar system (and dwarves along with it).
Elves are post-humans who have chosen to take on bodies, usually ones that they've designed themselves, in order to experience the novelty of life as a physically grounded being. Those on Adlivun have mostly tired of their immortality and have chosen to "go down with the ship," so to speak, living out their last years (millenia?) in their native solar system's final stretch.
Given all of that, humans (i.e., old-styles) are something novel in their own right. Some were created as play-things by the Inuit gods on Quidlivun (AKA Charon), some are descendents of old colony ship crews, some were born from bizarre sects that, for whatever reason, refused to transcend their humanity.
Most LotFP conventions work well in this environment (spells, unique monsters and magic items, etc.). We're currently working through B4 - The Lost City, having exchanged the desert of the module as written for the snow-blown tundra of Pluto's southern hemisphere, which only recently emerged from its decades of complete darkness.