The fun thing about writing a fantasy set in the future or in some alternate universe is, of course, you get to make up your own rules. Garret Jon Groenveld’s The Hummingbirds, a dystopian fantasy set in a future of indeterminate distance, has been kicking around for a decade or so, but it is currently making its New York debut at the Chain Theatre. Groenveld depicts a highly regulated society, yet a violent and anarchic one, and it’s debatable whether we’ve moved closer to such an environment since he wrote it. But no question, the man has imagination, and his vision is efficiently presented in a well-staged, well-acted little production.