The division of genres has become a speculative game of slots, and the meaning within those slots, and woe betide those who send in a query to an agent who reps books that are in Slot A, not Slot B.
Science Fiction Genre Characteristics
First, I’d like to make a small observation on my understanding of science fiction (I liked this bit from http://en.wikipedia.org/wiki/History_of_science_fiction): “. . . [a] deep integration of science and inventions into daily life [that] encourage[s] a greater interest in literature that explores the relationship between technology, society, and the individual. In recent decades, the genre has diversified and become firmly established as a major influence on global culture and thought.”
That would mean that anything I wrote would land squarely in one subgenre: social sci-fi. I thought it was the main reason for sci-fi. Apparently not.
At any rate, the first decision you make before you even begin to write, is will it be a children’s, middle grade, young adult, near adult, or an adult book? You decide which of those based on your protagonist’s age, not content. The age is not necessarily at the beginning or end of the story, but the bulk of the story.
Goodreads and Wikipedia Science Fiction Genres
The next step is to figure out in which slot your story belongs in. I found the list below on http://en.wikipedia.org/wiki/History_of_science_fiction. http://www.cuebon.com/ewriters/SFsubgenresR-X.html gets even more detailed. You can go really crazy and try to pinpoint as exactly as Goodreads does with this list of fifty(!) subgenres, but sifting that finely seemed overkill for this article. It’s good of Goodreads to do it, however: https://www.goodreads.com/topic/show/1656223-subgenre-challenge-sci-fi.
I’ve combined Wiki and Cuebon’s lists and grouped them as I thought they made sense.
Adventure science fiction / Space epic / Space opera
Anthropological science fiction / Social science fiction / Soft science fiction
Apocalyptic and Post-apocalyptic fiction
Arcanepunk / Science fantasy
Comic science fiction
Feminist science fiction
Hard science fiction
Horror / Weird science fiction
Military science fiction
Science fiction Western/ aka Space western
Speculative poetry / Science fiction poetry
Steampunk / Dieselpunk
Superhero or Superhuman or Supernatural fiction
I’m sure you appreciate that with each explanation of what fits in those categories, there are sometimes two or three divisions within each of the sub-divisions.
So, the challenge this time was a story that had these elements:
A spaceship crash lands on a ruined and almost-deserted planet. The captain is dead. The planet is occupied by rift monsters, demons, half-crazed humans who’ve been left for dead by Earth’s military (as not worth the risk of rescue) in a survival-mode town, poisonous radiation, a twenty-year-old girl with the gift of healing, and her eighteen-year-old super-strong brother who’s possessed by and aided by a rift god to do whatever the brother needs to do. What the brother and sister need to do right now is get on that ship asap, repair it, and learn how to fly it off the planet.
There’s lots of gory dismemberment with a magic ax, a succubus the rift god has sent to help them get to the ship and off the planet, creepy monsters, crazy-from-radiation townsfolk out to stop them from reaching the ship, the town whore’s daughter who can wield a hell of a knife, magic, technology, super-weapons, the ship’s security chief who’s gone mad from the radiation, too, and tries to kill them from a mini-helo. The story is also full of very adroit nods to what motivates people and how people interact, think, love, hate, and of course also the fear of the unknown.
Well, clearly (maybe not to you, but you haven’t had the fun of reading it), this is an near adult anthropological (study of man and his society), adventure, post-apocalyptic, supernatural, horror, arcanepunk (fantasy world where both magic and science exist) novel, right? :-}.
Researching your genre is fun and you can do it on your own, but why not have help? Professional editors do a lot more than just edit, and our knowledge base is wide and deep on the most unexpected things . . . like the difference between Steampunk and Dieselpunk.