Westworld is a 1973 science fiction western-thriller film written and directed by novelist Michael Crichton.

A amusement park for rich vacationers. The park provides its customers a way to live out their fantasies through the use of robots that provide anything they want. Two of the vacationers choose a wild west adventure. However, after a computer breakdown, they find that they are now being stalked by a rogue robot gun-slinger.

Westworld Movie Review
By Time Out

“Despite faults (chiefly a dispersal of its energies), a wonderfully enjoyable fantasy about a futuristic holiday resort offering robot worlds of exotic sex, romance or violence amid the licence of ancient Rome, the gallantries of a medieval chateau, or the gunslinging frontier town. Best and most fully realised of these worlds is the Western, with Brynner (brilliant) as the robot gunman required to die, bloodily, every time a greenhorn tourist challenges him to the draw. Until, that is, the robots begin to malfunction – or rebel: only the computers that designed them know exactly how they work – and the Brynner machine sets out, now part mad killer and part Frankenstein monster, in quest of revenge. Great stuff.”