Despite what many claim, haiku is not a tradition form, only going back a few centuries. As such there are NO set rules to haiku writing: They do NOT have to be untitled (as a writing teacher once told me, “If you don’t care enough about your work to title it, how can you expect an editor to care about it?”) They do not have to be about nature, or the elements and do not have to be mainstream: SF, fantasy, horror, mystery are all valid haiku themes.