Actually, Borderlands is post-apoc in many, regardless of not being set on Earth. Pandora once had a totally functional society, until the megacorporation that was funding the whole ordeal pulled out and left all its workers behind on the planet because it would cost to much to relocate everyone again. As a result, the entire planet was cut off from supplies, people went batshit insane and became raiders and so on. After other megacorporations took an interest, transit to & from the planet was possible again (but by then, the marbles had already been lost ). Qualifies as a apocalypse to me if 75% of your population turns into violent rage fueled killing machines, tbh.