I'd leave this classified as "science fiction," but it's really science fiction/dark fantasy/horror. In this novella, starships are powered by enslaved gods, there's a slightly Lovecraftian vibe to the story, and the ending is something out of a John Carpenter movie.
It's an entertaining, slightly weird page-turner, and I loved the dark fantasy/sci-fi setting right up until the ending, which I found both predictable and a bit rushed.