From Jules Verne and H.G. Wells to Isaac Asimov, Ray Bradbury, Ursula LeGuin, and William Gibson, science fiction is one of the most enduring and popular genres. Whether on the page or on TV and film ( , the franchise), it grips the imagination. For a science-fiction author, the dream is to go boldly where no one has gone before, but sometimes the writing seems to be going nowhere at all—and future, alternate, parallel, or speculative worlds just wont come into focus. Fortunately, this guide helps show the way, with 100 prompts for everything from alien invasions to cyberpunk and beyond.