How away from real world can we get? Is magic in the world allowed, or super advanced tech, or supernatural forces? Like... Would the worlds of the books of Nicholas Flamel/The Alchemist, or RWBY, or Mekakucity Actors, or Gundam, or any similar levels of extreme advanced tech., magic, or otherwise be allowed as an origin world, or are they not allowed because they're supposed to be timelines of the same world?