My next campaign:
YOU are a shipwrecked space traveler from Thundera, Eternia, Etheria or Mongo.
YOU've crashed down on a water-rich planet with a N-O2 atmosphere like your home. The whole planet is wilderness. The only natives who even have language, let alone know anything about tools, are small bands of hunter-gatherer simioids.
But someone crashed here first! The Mutants of Thundera, the Horde of Etheria, the Hawkmen and Space Vikings of Mongo, maybe even some Decepticons. And who left behind all these mazy ruins and abandoned temples of blasphemy?
Stay tuned, Space Wanderers!