Oh my children, my eyes are actually bleeding from all the garbage I've been absorbing so I decided to dig deep into my younger self and pulled up a real classic that was way ahead of its time. This movie was written and directed by Michael Crichton - so consider this movie your parent's (or God help me your grandparent's) Jurassic Park. Because the idea is basically there, except this vacation spot has classic time period spots instead of dinosaurs. And. This. Movie. Is. Awesome.
In the future, if you're really stressed and need to 'get away' the Delos Company has the spot for you. For just $1,000 per day (that's $5,154.64 in 2012 dollars, conversely 1,000 in 1973 money is only worth $194) you can escape to either Western World, Roman World or Medieval World. Each world has realistic androids that can do anything, they interact with you (including sex), fight with you, and you can even 'kill' them - they 'bleed' like real humans (or zombie targets). Peter (Richard Benjamin) is on his first trip with his friend John (James Brolin, oh I had a crush on him in the 70's) whose been there before and loved it. A hovercraft takes you across a large desert where you land and take a shuttle to your particular 'world'. Peter and John are going to Western World, which features a gunslinger programmed to start duels but always lose (Yul Brynner). For safety the guns react to heat signatures - they will only fire real bullets at cold objects (androids). Nothing can possibly go wrong (Didn't he use that same phrase for Jurassic Park?).
But at first, content that the fail rate of all the machines was 0.5% per 24 hour period, the technicians become worried as the fail rate has doubled, and is continuing to increase. They wonder if there is a 'disease' within the system (we would call that a computer virus). Yes, things can go wrong and do. Peter and John are having a blast however, having shoot-outs, hanging out in the saloon run by Miss Carrie (the beautiful Majel Barrett), and all the non-comforts of the 1880's wild west. That is, until while resting in a canyon they come upon a rattlesnake. Despite both shooting at it, it bites John. Oops. The failures get worse and the company board decides not to let anyone else in until it's fixed, but the present guests shouldn't be in any danger.
After a particularly rowdy night of brawling and drinking in the bar, John and Peter stagger back to their hotel - when they are confronted by the gunslinger. Both being hung over, John offers to 'take care of it this time' - but the gunslinger shoots first, wounding him, then shoots again. John's dead. Peter can't believe it but self-preservation takes over and he rides off on his horse, the gunslinger close behind.
Meanwhile the other two parks are in dire straights as well. The system was completely shut down, but none of the androids responded and all seem to have gone into murder mode - the three parks become littered with the bodies of the 'guests'. The control room desperately tries everything to get the system back up (it's trapped them in a sealed room), but eventually succumbs to lack of oxygen and heat.
Martin meets a fleeing technician, asks what to do and finds out that this android has special hardware for his sight and hearing as well as reflexes and no matter what Martin tries, he's going to die. He disagrees, showing some strength and courage. In Roman World, he climbs down through a manhole to the underground control area. Unfortunately, following the heat signature of Martin's footprints, the gunslinger follows him into the tunnels.
Remembering what the tech had told him, Martin grabs some hydrochloric acid and throws it in the gunslinger's face. That messes him up a bit, but he still can see heat signatures and his hearing is acute. In Roman World, Martin hides by lit torches, which the gunslinger cannot process - the heat of the torches and Martin seem the same to him - until Martin makes a noise. Then the gunslinger attacks and Martin sets him on fire. Thinking it's over, he rests - until the android slowly makes its way toward him. It falls to the ground, rolling over, and we see the empty shell of his head. Richard sits, exhausted and in shock with Delos' ad going through his head, 'Have we got a vacation for you!'