Alien, he proceeded to adapt Philip K. Dick's Do Androids Dream of Electric Sheep? and gave us Blade Runner (1982).
The importance of Blade Runner can't be overstated. To this day, it's hard for a science fiction film to not be inspired or indebted to it. Blade Runner envisioned a future that was not bright or optimistic but dirty, dark, and grungy. True, there had been dystopian movies before it that depicted a nightmarish future but none could compare to this level of detail or scale.
Los Angeles. 2019. The Tyrell Corporation has created Replicants, sentient beings that are indistinguishable from humans, to use as slave labor. A group of renegade Replicants have infiltrated Earth, led by Roy Batty (Rutger Hauer), looking for ways to extend their short lifespans. Because Replicants are outlawed on Earth, the police send Rick Deckard (Harrison Ford), an ex-cop who worked as a "Blade Runner," to hunt and eliminate the Replicants.
Blade Runner boils down to film-noir set in the future. The hallmarks of film noir all over the place: the burned out detective down on his luck, the dark urban environment, the overwhelming atmosphere of despair and corruption, and even visual hallmarks such as ceiling fans and shadows of Venetian blinds cast on the wall. In looking to the past, Scott crafts a paranoid, cynical future, one in which wall technology has marched on, but humanity remains petty, violent, and self-destructive.
In this world, Blade Runner asks what makes us human. The Replicants are artificially created, but they want what we want: more life. They're dangerous but strangely child-like, not having the years needed to build up memories and experiences to comprehend certain situations from an emotional standpoint. An empathy test is used to expose them because a human would be able to have a reaction to the hypothetical scenarios presented to them; a Replicant has none.
Deckard isn't much better, and he's the closest thing to a hero. It's one thing to terminate armed and dangerous individuals, but it's another thing to shoot a woman as she runs away, her only crime being on a planet that has outlawed her kind, even though the residents of this planet built her. The Replicants aren't angels (possibly fallen angels, though), but humans created them, gave them the short lifespans, mistreated them, and now fear them.
While the planet might be beyond salvation, Deckard might not be. Initially, he is dismissive toward the Replicants. After he meets Rachel (Sean Young), a Replicant with false memories implanted so she is not aware she's Replicant, he outright mocks her and is cruel, but gradually, he falls in love with her. This forces him to question everything he's been doing. Who is he to decide who's human and who isn't? Has he been a murderer, a hired killer, all this time? Of course, depending on which version of the movie you watch, Deckard could very well be a Replicant himself, so he could be executing people for the same crime he's guilty of himself.
The Matrix, and others. The future is not clean and pristine but dirty, smoke-filled, and grimy.
And yet, the film captures moments of beauty. Roy Batty does some awful things, but in a career-best performance by Hauer, he's not an evil villain. His final confrontation with Deckard is not a cold, ruthless fight to the death but a sad, poetic longing to be remembered. Ironically, Batty, with his final actions, demonstrates more humanity and compassion than just about anyone else in the film.