[@Sigma] So I'm thinking for my dudes they came upon a system in which initially each world was decent for human life having been Terraformed extensively by a previous species present. But unable to communicate the two got to war with my settlers eventually winning but as a final retribution the native xenos scoured their worlds with doomsday devices. The remaining worlds remained survivable but still terrible places to be leading to the people having to go into considerable cybernetics and genetic engineering to adapt to their new conditions, and thus the demographics would be 100% "transhuman" for it. Sound cool?