The mystery category starts with a crime, then resolves it by the end. Simple formula, with nearly infinite variations possible. Science fiction takes that premise and runs with it. Science fiction is a setting genre. As such, you simply start out with “Not Here, Not Now” (presumably a technological future and a surfeit of magic, or you would be in a fantasy category) and tell your story. Where you set your story (the world-building elements) can be pretty much anywhere. If you have magic, presumably you are in some sort of fantasy category, as noted above, but it might be…