Science fantasy

Science fantasy is a mixed genre within the umbrella of speculative fiction which simultaneously draws upon and/or combines tropes and elements from both science fiction and fantasy. It also sometimes incorporates elements of horror fiction.

Distinguishing between science fiction and fantasy, Rod Serling claimed that the former was "the improbable made possible" while the latter was "the impossible made probable". As a combination of the two, science fantasy gives a scientific veneer of realism to things that simply could not happen in the real world under any circumstances. Where science fiction does not permit the existence of fantasy or supernatural elements, science fantasy explicitly relies upon them.

The label first came into wide use after many science fantasy stories were published in the American pulp magazines, such as Robert A. Heinlein's Magic, Inc., L. Ron Hubbard's Slaves of Sleep, and Fletcher Pratt and L. Sprague de Camp's Harold Shea series. All were relatively rationalistic stories published in John W. Campbell, Jr.'s Unknown magazine. These were a deliberate attempt to apply the techniques and attitudes of science fiction to traditional fantasy subjects. The Magazine of Fantasy and Science Fiction published, among other things, all but the last of the Operation series, by Poul Anderson.

...
Wikipedia