A few years ago I ran a Starfinder campaign for a bit that was genuinely fun. It was a group of four players who were all quite in sync, and a real blast. One of the elements I enjoyed was the method by which I extracted a useful Starfinder plot: I took the core elements of the movie Conan the Barbarian and put the entire thing in space. In stead of a cult of Set it was a cult to Typhon. Instead of Thulsa Doom we had a renegade vesk (lizard man) whose temple was not in some mountain range but a floating space station filled with abominable horrors and mysteries. Pilgrims would flock from across the galaxy to come here, and the vesk cultists wore white robes with yellow trim. I riffed on perhaps 70% of that movie to great effect, and the net result was a blast, as well as me getting to enjoy a plot and pacing of a film I knew well, transcribed into a sci-fantasy setting.
That mixture of "movie-inspired plot/theme" mixed with a genre outside the scope of the source material has got me to thinking about other ways you could blend movies with unusual genre combinations. Any of this would work well in multigenre systems such as GURPS, Basic Roleplaying, Savage Worlds or Cypher System. Some examples that come to mind include:
The Road Warrior (Mad Max 2) but as an historical adventure set in the West Indies or maybe on the Silk Road. A lone trader or small group who journey the world of the 16th century stumble across a caravan or remote fortress besieged by raiders, seeking an incredible treasure;
Air Force One (the one with Harrison Ford)! but its a scifi Traveller-style setting on board a starship when foreign (alien?) invaders attack to seize the emperor of man;
Blackhawk Down, but its a fantasy setting about a team of dragon or wyvern knights who find themselves trapped in enemy territory during a brutal war;
Poltergeist, but it's set in a post-apocalyptic future where the house's "incursion" is caused by the horrific aliens/nanites/mutants that live outside the complex, which is the last bastion of civilization;
The Truman Show, but its literally a world focused on any other two genres you can pick outside of the great dome: maybe it's scifi (a small worldship and maybe kidnapped by aliens), or post-apocalypse (the PCs are kept pets by robots who maintain an imaginary world for them), fantasy (cruel subjects of a mad wizard's experiment), or even modern day, but its all part of some bizarre top secret experiment;
Alien, but its in the 1720's in the Caribbean and the eponymous entity is actually a loasummoned by a houngan/bokor found in a mysterious derelict ship;
The Thing, but its a realm of sword & sorcery and the imperial outpost is at the edge of the known world, protecting from unknown monsters when a lone rider on a horse chasing a hound arrives at their doorstep from the watch tower 100 miles away....;
The Matrix, but its a demonic hellscape where demons or devils have trapped humanity in an ageless sleep, dreaming whatever nightmares are conjured up, to which a small few awaken to serve as resistance fighters against the abyssal hordes. Alternatively, the world of the dream is fantastical itself, but the reality is that humans who awaken find they are part of a society of magical godlike beings who use the deliberate limitations of the matrix/dream for their own amusement, and discard awakened humans like chattel; the humans, of course resist!
Anyway, you get the idea! The key elements to make this work are to find a solid basis for the story/plot outline from a good movie, then make it unrecognizable with the trappings of a different genre. For this to work, the dichotomy needs to be stark when contrasted; for example, in Starfinder when I borrowed from Conan the Barbarian no one got the feeling it seemed familiar to them because it was using trappings of the setting, and comparisons (such as Thulsa Doom's compound) to the movie were parallel but not exact (mountain temple vs. floating haunted space fortress).
Of the examples I provided above, a fine example would be The Truman Show, in which maybe not unlike the classic Dreampark novels maybe the Truman Show itself in this setting is a devised world using technology to ape magic, and people dropped in to it are deliberately treated to forget who they are; when the unreality of the universe becomes apparent, the PCs eventually expose it for a lie, only to discover that the real world outside is so much stranger!