You can think of speculative fiction as a kind of super-genre. Stories that live under this broad umbrella all deviate in some way from the laws and rules of everyday reality. That could mean they’re set in an entirely invented reality or in a world mostly like our own with a few minor tweaks, or anywhere in between.
The term speculative fiction was first coined by Robert Heinlein in the late 1940s, so it’s hardly a new concept. Its associations have shifted over the decades, though, from a term mostly syonymous with sci-fi to one that’s more fluid. In today’s parlance, speculative also includes fantasy and most horror, as well as stories that exist between the borders of these genres. It’s become an especially popular term among those who write settings or tropes from fantasy and sci-fi in a literary style.
One of my favorite things about Jordan Peele’s movies as a whole is that they don’t fit neatly into any genre box. A big reason for this is Peele’s worldbuilding style and prowess. His films take place in worlds that are just slant of reality: normal on the surface, but with one strange, horrifying difference lurking below—quite literally, in the case of Us, and metaphorically in his debut Get Out. It’s a similar thought experiment model that underpins many episodes of Twilight Zone, and it makes sense that Peele is at the helm of that reboot.
(Note: Thar be spoilers past this point. If you haven’t seen Nope and care about such things, probably best to stop reading now.)
