In 1973, Michael Crichton imagined a theme park of the future: Robots so realistic they were played by human actors and populated a Western town where guests could play cowboy. In the film Westworld, the robots went berserk and the Gunslinger (Yul Brynner) started shooting the paying customers for real.

Today HBO presents Westworld as an ongoing TV series that more deeply explores the idea of a robot theme park than a single film. The robots hosts of Westworld entertain human guests by interacting with them in complex storylines, having sex with them, and being killed by them. There are also human scientists who work for Westworld maintaining the robots — cleaning them, for instance, and putting the pieces back together after a guest has maimed, mangled, and killed a host.

A show like Westworld inherently comes with a lot of rules, scientific rules that the fictional technology will have to follow, as well as rules of the theme park itself. Some of these rules will be apparent when you watch the series, but others are implied.

When HBO presented Westworld to the Television Critics Association over the summer, we spoke to series creators Jonathan Nolan and Lisa Joy, and stars Evan Rachel Wood, Thandie Newton, James Marsden, Ed Harris, and Anthony Hopkins. They revealed 11 rules that make their take on Westworld unique.

1. THE GUNS ONLY “KILL” ROBOTS

This Westworld seems to have a safeguard against the Gunslinger scenario. We see in the very first episode that hosts can shoot at guests, but the impact seems less than that of a BB gun. It certainly doesn’t draw blood. With the same guns, the guests can blow the hosts away, but then the hosts still come back the next day.

“It’s not the guns,” Nolan said. “It’s the bullets. We thought a lot about this. In the original film, the guns won’t operate guest on guest, but we felt like the guests would want to have a more visceral experience here. So when they’re shot it has sort of the impact. They’re called simunitions. The U.S. military trains with rounds like the ones we’re talking about. But there’s a bit of an impact, a bit of a sting. So it’s not entirely consequence-free for the guests.”

2. YOU HAVE TO SIGN A RELEASE FORM

Even with simunitions, you’ve got to imagine there are plenty of chances for guests to get hurt. Simunitions won’t stop other guests from attacking them, horses from accidentally trampling them, or the guests themselves stumbling off a cliff or impaling themselves on a cactus.

But that’s what a liability waiver is for.

Nolan says he imagined clients signing a very comprehensive release form before being admitted to Westworld. The first episodes don’t show the guests filling out paperwork, but we heard it straight from Nolan.

“One of the ideas was sort of layered in the narrative,” Nolan said. “I think the release that you would sign when you came to this place would be pretty extensive, would cover a fair amount of injury and risk involved in going to Westworld.”

3. THE HOSTS ARE ALSO LIFEGUARDS

The episodes reveal that the hosts’ are programmed to look out for the guests, not to just to be a bank robber or a saloon keeper or a lady of the night. If action is putting guests in jeopardy, the hosts will — should anyway — steer the scene back into safety.

“Part of what the hosts have been designed to do, we have a feature in the program called The Good Samaritan Reflex or Function,” Nolan said. “Wherever they can, the park is populated by hosts and part of their responsibility, part of their subconscious programming is to try to protect the guests in whatever capacity it can. So if you’ve got a drunken guest who’s careening towards a cliff edge, you’re more likely than not to have a host nearby who, without breaking that narrative, is going to find a way to gently steer them back. They’re cannon fodder on one hand, but they’re also the all-purpose minders of this place.”

4. IT’S THE LITTLE THINGS THAT GIVE AWAY THE HOSTS

So you’re enjoying your stay in Westworld, meeting good people, and the hosts are so realistic you can’t even tell who’s a robot and who’s just another guest of the park like yourself. The actors who play hosts pointed out some of the things they are doing to distinguish their characters from humans. Evan Rachel Wood plays a central host, Dolores.

“I think we settled on this place of subtlety,” Wood said. “Those were the things that made the differences between the hosts and the humans very unsettling: because you can’t really tell them apart until there’s just one slight little movement, or shift, or freeze, that just throws you off completely. Those are the moments in the show that made me slightly scared, but really fun to do.”

5. THE HOSTS MAY BE MORE HUMAN THAN HUMAN

HBO’s Westworld is going to get into some deep existential issues about how human are the robots, and how inhuman are the guests who abuse them? Or even how human are the people who created the hosts? For one actor, playing a host made her feel “exquisitely human.” Thandie Newton plays Maeve Millay, one of the ladies in the Westworld brothel.

“I actually found every time I played the character, it was like a meditation,” Newton said. “I felt more perfectly, beautifully human, exquisitely human than I’ve ever felt, just by nature of the simplicity and how definite these characters had to be. Of course the show throws up so many existential questions about the nature of being human and do these hosts actually end up reflecting us more perfectly than we are? So making sure that we establish the engineering and the physicality of our characters was hugely important, and we had to start with simplicity because it’s going to go on a journey.”

6. IT’S BEEN AROUND AS LONG AS DISNEYLAND — OR LONGER

One character in Westworld has been a customer for 30 years, and the show suggests the park has been around even longer. While they haven’t yet specified a year in the future in which the show takes place, Nolan likens the longevity of Westworld to the real world legacy of Disneyland in our present day.

“We came up with an early estimate number which I’d hate to relate,” Nolan said. “One of the ideas that’s gently touched on, in our world this park has been extant for more than 30 years. You drive around L.A. and you see the Disney 60 signs. Disneyland … ours is very, very different but the idea of a fantasy world that you’d think was compelling enough to last generations. You’d take your grandkids to Disneyland and regale them with the stories of when they were there originally, 60 years ago. If you create something in this fantasy space that was powerful enough, lasting enough, it becomes an institution. We imagine in our show that Westworld has become an institution, a place that people can come to and they bring their kids back to.”

7. IT’S THE HOSTS’ (WEST)WORLD — WE’RE JUST VISITING

A big difference between Westworld the movie and Westworld the show is that the movie was really about the guests who go on vacation to the robot cowboy theme park. The show is really about the hosts who live here day in and day out, following their programming and sometimes creating their own. Guests enter, but we meet the hosts first.

“This is an examination of human nature from within and also from without,” Joy said. “We wanted to first ground it in the point of view of the hosts. We wanted to develop an emotional connection with them so that they could be fully personified and fully realized. So we made a very conscious choice to start this series through the point of view of Dolores — played by Evan Rachel Wood so beautifully — so that we could fully be with her in believing the reality of the West, and the love that she feels, the familial connections that she had. And after establishing that empathy, we start to broaden the world, not only examining the lives and perspectives of the guests who come into the park, but also the technicians who work within the park below the ground.”

8. IF YOU STAY LONG ENOUGH, YOU’LL FIGURE OUT WESTWORLD’S SECRETS

Ed Harris plays the 30-year Westworld veteran. He’s come up with a persona, The Man in Black, who seems like a villain in the pilot. Harris promises that the more he throws Westworld into chaos, the more his plan will be revealed. No matter how cool robots are, you don’t keep coming back for 30 years just to ride horses and shoot robots.

“There’s a much deeper purpose for him being there by this point,” Harris said. “He thinks there’s some deeper level to what’s happening in this park. He thinks perhaps Tony’s character is in charge of something that is not really obvious on the surface, and he’s probing. He thinks the more chaos he causes, the more destruction he can create with these AI folks, it’s not random. He is not just going around killing everybody he sees. There is always some narrative going along that he’s following that somebody gets in his way, and he has to blow them away.”

9. WESTWORLD IS NOT JUST ANY WESTERN, IT’S A JOHN FORD WESTERN

In 2016, audiences have seen so few westerns that each one may look unique. But if you’re a fan of the genre or you’ve been watching Westerns since Hollywood’s Golden Age, you might recognize the town that plays Westworld.

“When we talked about doing a Western, we went to that classic iconic sense of the John Ford Western, the Western where that geography is exquisitely exclusive in America,” Nolan said. “It turns out, John Ford had obviously made Monument Valley famous with is first films. His last four films shot in a place called Castle Valley (Utah) east of Moab, which is where we went back to for that. It’s incredibly beautiful.”

10. THE PLAYER PIANO IS TAKING REQUESTS

If you go into the Westworld saloon, there is a player piano churning out old timey music. If you listen really closely, you might recognize some of the songs from the ’90s grunge era or even classic rock. “Black Hole Sun” and “Paint It Black” are part of the piano’s playlist, and Nolan commissioned a real player piano to make the music.

“Part of the fun of it, once we clear the song, is to create an arrangement of the song that can then play on a player piano,” Nolan said. “Then we have a little company that we found in Southern California that still operates for all this time, and they can create the paper reels that we then thread into several actual player pianos. They’ve all been carefully restored. So this company can create the reel with that piece of contemporary music on it. There was a piece of Radiohead in the second episode as well, so we get a Radiohead song, we create our reel and we put it through. It’s really, really cool. It’s been a lot of fun.”

11. CLEAR YOUR HISTORY AFTER YOU PLAY THE ROLE

At least this is what Sir Anthony does. The Oscar winner plays a scientist who developed the artificial intelligence and faces conflicts when the hosts disobey his programming. Once he’s played the scene though, Hopkins moves on.

“I have a delete button in my brain,” Hopkins said. “I don’t remember the past very well. We started [Westworld] two years ago, and I was just watching it now. I had forgotten I was in some of those scenes. I seem to be cast over the years as a control freak. I don’t know why, because I’m not that at all. I hope not. I have a kind of diffident attitude about things, which has come with age, I guess, over the years. But they are fascinating parts to play, so obviously I can tap into some.”

Westworld premieres Sunday, October 2 at 9 p.m. on HBO