The Tension Experience first kicked off in February as an under-the-radar alternate-reality game dubbed Indoctrination. Players that found its website slowly learned about an entity called The O.O.A. Institute, and as they were pulled into real-world meetups, dead drops, and invasive personal interviews, the Institute's mythology began to take hold. It was all backstory to the September opening of Ascension, with Bousman and a cast of 40 actors taking over a 45,000-square-foot warehouse to create an interactive two-hour play, where the direction and storylines are dictated by the way players behave and interact with the other characters.

It's a step into a very different world for Bousman, who first burst onto the film scene in 2005 when he took over the Saw franchise. Box-office success and multiple sequels followed, but the filmmaker became disenchanted as the years wore on. "Filmmaking became so… I don't want to say mundane, but everyone with a camera was making a movie. Netflix was over-inundated with every fucking thing in the world, and it became hard to make an impact," he says. "I wanted to forge my own way. And Sleep No More changed me."

Bousman's introduction to that groundbreaking production, in which audience members walk freely through a re-created 1930s hotel and bear witness to a play inspired by Macbeth, pushed him in a new creative direction. He took in other immersive productions like The Drowned Man, Delusion, and Alone, turning to their creators to understand how the medium worked. "Four years ago, I did Blackout. I met with them, and I was like, 'I want to make my own. I want to do The Game in Los Angeles.'" (The echoes of that film, in which a banker's world is upended by a real-world game that may also be a con to ruin his life, can be seen in Tension from the early days of the ARG.)

When I arrived in an abandoned parking lot to experience Ascension for myself, I didn't know what to expect, nor did the other nine people in my group. A few hours prior we'd all received mysterious emails warning us not to attend, along with a letter from the Institute with some basic guidelines for our "processing" — things like "wear comfortable, modest undergarments," and clothes we wouldn't mind getting stained or ruined. (I ended up happy I paid attention on both counts.)

Was I okay with public nudity — including my own?

Moments later, I was in a van with a black hood over my head, being driven wildly through the streets of LA, then dumped alone outside the unmarked entrance of the O.O.A. Institute. Inside the impressively detailed waiting room, complete with magazines and inspirational posters, a no-nonsense secretary told me to fill out an application that had some more-than-unnerving questions. (Was I okay with public nudity, including my own? Who knew I was there, and what was their phone number?) Then I was off to a disheveled file room, where an elderly gentleman took my picture before he leaned in and offered a final warning: it wasn't too late to turn back. If I wanted out, I just had to say the magic word: "coward."

 Derrick Hinman / The Tension Experience

It's a fantastic way to set the mood, and to pull participants into the surreal, detailed world that Bousman and co-writer Clint Sears have dreamed up. Going into too many specifics about what happened to me would ruin the sense of mystery that makes Tension so fascinating, but I will say that while there were some typical haunted house activities — getting shoved through the dark, being forced to blindly touch unsavory things — I wouldn't necessarily call it a "horror" experience in the traditional sense. It's a psychological one. Once I realized the degree to which I could actually interact with the characters I encountered, a weird metamorphosis took place. I not only felt like I was the lead character in my own dark, twisted story, but I increasingly became engaged emotionally.

That feeling crescendoed late in the evening, when in one particularly harrowing moment — pressed by a mysterious, masked stranger, for reasons I'll keep secret — I found myself spontaneously opening up and apologizing for ways in which I'd failed friends and family members. It was the kind of scene that I could have theoretically lied my way through, but the events of the evening robbed me of the ability to keep the show's world at arm's length. I was simply there, inescapably present, as the madness of the night swirled around me.

The Tension Experience went beyond what I was expecting — mixing fear, empathy, and the sheer visceral thrill of discovery into an unsettling combination that still has me sitting up at night. It isn't just a Halloween stunt; it's a raucous step forward in a new and evolving storytelling medium that has as much in common with text adventure and video game mechanics as it does with scary movies. The point was driven home when my group reconvened at the end of the show, to discover that our choices and fears had led each of us through radically different scenes, plot points, and dramatic moments.

"It's a 400-page script," producer Gordon Bijelonic tells me, and every performer has between six and 12 possible scenes. Different keywords can activate a given actor's entrance into the storyline, and if an audience member never hits upon the right words during their conversations in the show, an actor could conceivably just stay in the shadows. "He doesn't even show up. He just sits there all night. So that's the good thing. You could come two or three different times, and you're going to have two or three different experiences."

It's like a real-life, walking and talking Telltale Games adventure, and like those titles it can push unexpected emotional buttons. For Bousman, that's precisely the point. "The whole reason I wanted to make movies was to get a reaction out of an audience member, to make them feel something. I make people feel every night with this, and I see it," he says, gesturing to the video screens. "I see them walking out crying. I see them walking out mad. I see them walking out enraged. And it stays with them, because they're not sitting in a theater watching; they are it. They're in the middle. They are a character. And to me, as an artist and a storyteller, that makes me so happy."

While Tension certainly isn't for everyone, it's impossible to argue that it doesn't accomplish Bousman's goals. And while it clearly pulls inspiration from the scarefests and theatrical productions that came before it, its grand ambition is undeniably significant. Future productions are planned under the names Adrenaline and Lust, Bijelonic tells me. "Our goal is to be the Cirque de Soleil of this world."

If anything, it seems like Tension is coming along at just the right moment, as the rise of virtual reality and an ever-increasing influx of interactive-theater productions are bringing the general concept of immersive experiences into the mainstream. Whether viewers are losing themselves in virtual worlds, walking into haunted houses or interactive plays, or simply dressing up and taking on fictional personae at comic conventions, they're increasingly interested in moving beyond the passive relationship they've had with traditional narrative mediums like film and television. This is a richer, more engaged kind of fandom, one that can invoke feverish levels of devotion. And for Bousman, that's a two-way relationship, with his audience causing the show to evolve and transform even after it's opened.

"This is the future. It is engaging an audience on a visceral, living, breathing art-form level," he says. "They are manipulating the story, not us. Their choices, who they like, who they respond to — who they don't. These things get written out; characters die. I think that's what is amazing about this, is that I get to sit back and watch it happen, but the audience is in control."

The Tension Experience: Ascension is currently scheduled to run in Los Angeles through the end of October. Tickets are priced at $125.