In August 2013, HBO announced plans for a TV adaptation based on the original film.
In the near future, there is a high-tech, highly realistic adult amusement park called Delos that features three themed "worlds" — Westworld (the American 'Wild West' from the 1880s), Medieval World (medieval Europe), and Roman World (pre-Christian Rome). The resort's three "worlds" are populated with lifelike androids that are practically indistinguishable from human beings, each programmed in character for their assigned historical environment. People pay to indulge in adventures in each of the worlds where they interact with the android population. Guests are encouraged to do anything they feel like, including killing any of the androids or having sexual intercourse with the gynoids (feminine robots). The film begins with a TV commercial where a Delos employee is interviewing people at the airport who just returned from Delos and are pleased with their stay, and the employee announcing "Boy, have we got a vacation for you!"
Peter Martin is a first time visitor. He and a friend, John Blane, a return visitor, are taken by hovercraft to Delos' resort in the middle of the desert. The hovercraft disembarks at an underground processing facility. Guests are segregated by color-coding, through yellow (for Roman World), red (for Medieval World) or blue (for Westworld). The guests are attired in clothing appropriate for their chosen period and sent down a tunnel which surfaces in the respective "world". Much of the film is shown with Peter and John in Westworld, although it intersperses with some of the other parts of Delos.
In Westworld, Peter sees that Delos is strict about historical accuracy, right down to the artifacts having been made in the actual years. John says they can use their guns to kill androids, but Peter expresses concern about who is who, considering the androids look identical to guests (with exception of small indentations on the hands). John challenges Peter to shoot him, but when Peter does so, his pistol fails to discharge. John explains that the pistols have heat-sensitive trackers. Androids have a low body temperature, but the pistols do not fire if they detect a certain heat range, in which case they will not activate near the high body temperatures humans are known for. Peter remarks that Delos thought of everything.
The technicians running Delos notice problems are beginning to spread among the androids, but things go wrong in attempts to shut down power and the androids. Running on reserve power, the robots run amok and Delos becomes a death trap for its guests.
- Yul Brynner as The Gunslinger
- Richard Benjamin as Peter Martin
- James Brolin as John Blane
- Norman Bartold as the Medieval Knight
- Alan Oppenheimer as the Chief Supervisor
- Victoria Shaw as the Medieval Queen
- Dick Van Patten as the Banker
- Linda Scott as Arlette, the French prostitute
- Steve Franken as the Delos Technician shot dead by the Gunslinger
- Michael Mikler as the Black Knight
- Terry Wilson as the Sheriff
- Majel Barrett as Miss Carrie, madame of the Westworld bordello
- Anne Randall as Daphne, the serving-maid who refuses the Medieval Knight's advances
- Nora Marlowe as the Hostess
- Robert J. Hogan as the Delos Guests' Interviewer (uncredited)
- Westworld is the first feature film to use digital image processing to pixellate photography to simulate an android point of view.
- Majel Barrett, who plays the madam, is best known as portraying Nurse Chapel and the voice of the computer in Star Trek (Original Series and Next Generation) and for a recurring role in Star Trek: The Next Generation (Deanna Troi's mother, Lwoxana Troi). Barrett was the wife of Star Trek creator Gene Roddenberry.
- Westworld describes the concept of a computer virus extremely early in the development of networked computers, when computer viruses were almost unheard of.
- Westworld is the first time the concept of "intelligent machines (computers) creating other intelligent machines (robots) without human involvement had been described.
- According to the original filming script, the Delos Resort Complex is located inside a climate controlled dome 500 miles from the edge of the Sahara Desert.
- Guests paid $1000 per day to stay at the Delos Resort in the 1973 film. The per day cost to visit the park (HBO series) was quoted by Logan at $40,000.
- Guests were transported to the resort via hovercraft.
- The name of the park was repeatedly identified during the movie as "Western World", while the film was titled "Westworld". The name of the park and show's title remain consistent on the HBO series.
- The system of tunnels running beneath the park complex and the computer control room was inspired by the "utilidore" system and the DACS (digital audio control system) room beneath the Magic Kingdom Park at Walt Disney World in Florida. DACS is/was located beneath Fantasyland. The Magic Kingdom opened in 1971, two years prior to Westworld.
- The tagline, "Where nothing can possibly go worng" (sic) appeared on promotional materials (including the movie poster on the cover of the "shooting" film script now available on Amazon).
The full movie (in 720p) is on YouTube for free.