A posthuman species who developed on a world with a large amount of ruins and technology left over from the Star People.
From Nobody to Nightmare: They started out as a normal posthuman species, albeit one that advanced quickly technologically thanks to leftovers from the Star People. And yet, they eventually became The Gravitals.
Low Culture, High Tech: The Ruin Haunters built up their civilization by re-creating the Qu's and Star People's technology, but they rarely had any idea how any of it worked.
Names to Run Away from Really Fast: A xenophobic posthuman species with access to nuclear weapons that just so happen to be known as the Ruin Haunters.
Nuke 'em: Are said to have used various thermonuclear weapons in two of their planet-spanning wars. This "hardened and awakened" them.
World War Whatever: Before evolving into the Gravitals, the Ruin Haunters had five consecutive world wars, two of which were fought with thermonuclear weapons.