In this Science Fiction Trope it is revealed that the Gods or Mythological Creatures of the distant past were real, but were "merely" aliens. This lets you blend Sword and Sorcery with spaceships and mecha, and set it all in Prehistory.
Some more things the Ancient Astronauts might have been responsible for:
- The Pyramids of Egypt
- The Statues of Easter Island
- The Nazca Lines
- The Ark of the Covenant
- The Visions of Ezekiel
- The Piri Reis Map
Books: Chariots Of The Gods by Erich von Däniken
Game and Story Use
- Always a fun twist, even if it is pretty cliched at this point.
- Could use it to suprise the PCs in a Time Travel campaign, should they go back far enough in time.
- Or the PCs could be the Ancient Astronauts. Have them stuck in the past, or crash on a primitive world, and use whatever science and tech they brought with to put themselves at the top of the food chain.
- Ancient Myths could be paralleled in a Space Opera or other sci-fi setting. Base your PCs and NPCs on classical heroes and Gods, and tell the tale of Troy or Ragnarok set against a backdrop of the stars.
- Could be the secret truth behind an Out Of Place Artifact.