Pentapods, provolutionists. Space horror... transhuman technothriller... they would offer something different and unique to 2300.
Imagine playing Flatlined in the 2300AD setting but as you discover more about yourself you find out that you are actually a pentapod human bullet
or while exploring a derelict settlement you discover strange pentapod eggs that sample your DNA... Invasion of the body snatchers, Alien, Bladerunner...
as to the provolutionists...