Well before the TV series it inspired (which didn't grab me), Westworld was set in Delos, an expensive high-tech amusement park divided into three "lands" - Westworld, Romanworld and Medievalworld.

Guests could live out fantasies that fit in to the respective environments - gunfights, orgies, jousting, indulge in whatever sex, violence and adventure they wanted.

Two men, confident returnee John (James Brolin) and his timid, recently divorced friend Peter (Richard Benjamin) come to Westworld.

It takes a while for Peter to accept it's all pretend and safe but soon he's shooting, whoring, bar-room brawling and living it up in general.

A computer virus invades Delos's sophisticated technology and things start going wrong. Soon the robots run amok, killing the guests. In Westworld, the Gunslinger Yul Brynner begins stalking our heroes. He kills John and Peter must work out a way to defeat his stronger, faster mechanical enemy.

Westworld was Michael Crichton's cinema debut as a writer-director and an obvious influence on his later novel, Jurassic Park (much the same premise except with dinosaurs instead of robots).

There are plenty of nits to pick here - such as, even in normal operation, how can guests' safety be guaranteed when there's plenty of imminent physical danger? And why isn't there a manually operated way for the technicians to escape?

The film also suffers from the limitations of its low budget - it has a TV-movie look and more could have been done to flesh out the worlds and the people in them. There were some scenes filmed but deleted - unfortunately they haven't resurfaced.

More forgivable is the now-dated technology depicted (which does, however, look modest for a place of such size and scope). Westworld has been cited as the first movie to use computer imagery - the pixellated couple of minutes of footage depicting the robot point of view took four months to complete, with the computer processing taking about eight hours for a 10-second sequence. It's rudimentary, but it was a start, and the technology is used in the service of the story rather than dominating it.

Despite its limitations, Westworld is lots of fun. You can look for deeper themes about masculinity and technology or just go along for the ride.