Just some random ideas I had, three cents worth. Maybe something like Vargr from Traveller ( https://wiki.travellerrpg.com/Vargr ) Animal / human hybrids taken from earth by ancient aliens in the distant past and planted to a new planet. New species should be doable, if we keep normal human body (just add tail) and some animal-like heads. (Assuming the clothing works like it does in oblivion/skyrim/fallout) should be fairly doable, harder if the custom race is playable. They should have some "weird" quirks in their society so that it would be interresting for regular humans to explore their homeworld. Maybe entirely different cultural norms, depending on wich species they are based on.