I've written a science fiction book that has a strong feel of "fantasy." Three quarters of the story is in a medieval/primitive kingdom type settings (think Game of Thrones or Wheel of Time). There are gods and supernatural gifts that some characters have been given. There are no aliens. All the worlds are are peopled by humans, though the animal life varies. There are also portals that connect the worlds. The gods created the portals and created the universe, and there are lots of spiritual/metaphysical questions raised in the book like, such as, why is there suffering in the world and does it have a purpose.
But what makes it sci-fi is that some of the worlds have advanced cultures with starships and such.
I don't want to upset readers expectations and mis-identify the genre. Readers want to know what they are getting. What sub-genre best fits this type of story? Space Opera? Portal fantasy?
Any thoughts or feedback would help. -Brandon Barr