Glad it was deleted, in my opinion it was purely sci-fi. Some made the piont that it has horror "elements" but yhat alone should not qualify it as a horror film. Many movies have horror elements but are nowhere near horror movies. Rambo is a good example, tons of gore and splatter but not even close to makeing it a horror film.
Genres are mixed and mashed quite often these days, tons of movies have comedy elements but I would not consider them comedys. To me like Lon said, if you look at the main theme of the film its usually quite obvious what genre it fits into the best.