Harrison Ford stars as "Blade Runner" Rick Deckard.
In the future world of the movie artificially manufactured androids or "replicants" are used for dangerous and degrading work in Earth's "offworld colonies". Replicants are considered dangerous and are illegal on Earth, and the Blade Runners are bounty hunters who track down and "retire" (kill) any trespassers. Deckard is called out of his own retirement to "retire" several advanced "Nexus-6" replicants who are illegally present in Los Angeles.
Blade Runner operates on an unusually rich number of dramatic levels. The movie's dark cyberpunk style and futuristic design have inspired many subsequent science fiction movies, The Fifth Element and The Matrix for example. It also owes a large debt to film noir, containing such conventions as the femme fatale[?] and the questionable moral outlook of the Hero - extended here even to include the humanity of the hero, as well as the usual dark and shadowy cinematography.
But it is also perhaps the most literate science fiction work of recent years, both thematically -- enfolding the philosophy of religion and moral implications of the increasing human mastery of genetic engineering, within the context of classical Greek drama and its notions of hubris -- and linguistically, drawing on the poetry of William Blake and the Bible.
Wikipedia contains spoilers--the following will discuss plot in detail.
Six versions of the film exist but only two are widely known and seen:
Ridley Scott decided both the voice-over and the happy ending were not suited to the movie. The ending in the Director's Cut has to do with the following included scene: Deckard picks up a small origami unicorn he noticed on the ground when it was knocked over by Rachael as she was walking towards the elevator. This suggests Gaff knew about his dreams, insinuating that Deckard too has fabricated or copied memories, making him a replicant as well.
Scott ended much speculation on the issue stated in a 2002 interview that Deckard is indeed a replicant, although this raises a number of obvious questions.
In 2002, Scott completed a new cut of the film - creating a new digital print of the film from the original negatives, updating the special effects, and remixing the score into 5.1 surround. Unlike the rushed 1992 Director's Cut, Scott personally oversaw the new cut. As of 2003, this "Special Edition" release has been delayed for unspecified legal reasons, but is expected before the end of the year. It is said to be a three-disc set including the original theatrical release, the 1992 director's cut, and the newly enhanced version, as well as deleted scenes, interviews, and a BBC documentary.  (http://www.brmovie.com/BR_Special_Edition.htm)
Three Blade Runner novels, sequels to the movie, have been written by Phillip K. Dick's friend K. W. Jeter:
There are also two computer games based on the movie. One for Commodore 64 and ZX Spectrum by CRL Group PLC[?] year 1985 and one PC game (Westwood Studios, 1997), based on the world described by the film.
The world of Blade Runner realizes a future whose fictional distance from present reality has grown sharply smaller during the past twenty years.
The first draft of the entire human genome was decoded in June 26, 2000 by the Human Genome Project, followed by a steadily-increasing number of other organisms across the microscopic to macroscopic spectrum. The short step from theory to practice in using genetic knowledge was taken quickly: genetically modified organisms have become a present reality, with genetically-modified food ingredients an everyday part of human daily diet (at least, in North America).
The embryonic techniques of somatic cell nuclear transfer from a specific genotype via cloning, as well as some of the senescence[?] pre-figured in "Blade Runner", were demonstrated by the cloning of Dolly the sheep in 1996. Since 2001, political efforts have been mounting in many countries to reflexively ban human cloning, impelled by a sense of its abhorrence and imminence, while rumors abound that that the first human clones may already have been produced.
In all these developments, a clear tension between commercial and non-commercial interests is apparent, as scientific and business motivations conflict with religious concerns about the appropriateness of human intervention in the deepest fabric of nature.
Such issues are deeply troubling to many. At core, the creation of life and the ordering of the natural world has been the traditional raison d'etre of gods, and the substance of various creation myths. In the classic Greek tradition, the term hubris denotes actions by humans that usurp on roles properly reserved for the gods; heroes who display hubris invariably meet nasty ends. Blade Runner masterfully immerses us in these conflicts, successfully blurring any standard expectations of moral correctness.