Horror may be cyclical in Hollywood, but there’s one sector where fright always sells.Haunted houses have generated a thriving, nationwide industry that attracts every demographic from grown-up comicbook geeks to teenagers with money to burn, and in New York, a team of theater vets is using its legit sensibility to woo them. Created in 2004 by Off Broadway director and publicist Timothy Haskell (“Road House: The Stage Version”), “Nightmare Haunted House” is becoming a local institution. Known for fusing audience interaction, sophisticated design and theatrical narratives, “Nightmare” has enjoyed capacity crowds and solid reviews from both mainstream and horror-focused press. Now, says producer Chip Meyrelles (“Bug,” “The Lieutenant of Inishmore”), who came aboard in 2005, plans are afoot to extend the brand beyond the fall calendar and into other media. But first, there’s this year’s house to manage, which is installed at Off Broadway venue the CSV Cultural Center. Meyrelles says he expects 35,000 to 40,000 people to visit “Nightmare” during its Sept. 28-Nov. 3 run. With a $60 top ticket price, that leaves plenty of room for profit — the budget runs several hundred thousand dollars — but it also brings challenges that most legit producers don’t face. Of the 30 actors, most are college students with little professional training, so Haskell says he’s learned to write for performers who can’t sell the same scene for hours on end. “I’ve had to make it bad-actor proof and think of rooms that are more concept driven,” he explains. One high-concept offering made auds feel like they were being buried alive: They had to crawl into a low chamber with a plexiglass ceiling and watch as an actor dumped dirt over their heads. Though it was popular enough to be used in multiple seasons, the experience also disturbed several patrons. Less high-concept is the narrative that threads through the “Nightmare” experience. Last year’s house, dubbed “Face Your Fear,” had auds viewing a little girl getting terrorized before falling through her bed only to reappear in the crowd to lead them through the rest of the house, with each room being one of her fears. “We want people to care about the characters, so that when something awful happens to them, it’s that much more horrific,” Haskell says. As for this year’s house, subtitled “Ghost Stories,” it will have several characters as guides instead of a single protagonist. Auds should also expect to interact with the story in front of them. “You think about not making it too scary. I get a little concerned, but then, that’s what people pay for,” Haskell says. Hence another obstacle: People do pay to be horrified and expect completely new scares each year. Creatives are under constant pressure to top themselves. And some tactics don’t work: Last year’s “Nightmare” featured a different house in each of the five New York boroughs, which was a logistical nightmare. There’s just one Manhattan venue this season, and it boasts an added feature called the Maze, which sends patrons through a darkened labyrinth. Auds are encouraged to feel ownership of the show. Many of the rooms in this year’s house were inspired by fan emails describing paranormal experiences. The emails were solicited weeks ago, which helped get people thinking about “Nightmare” well before Halloween. That’s one of Meyrelles’ primary goals. “When you have a seasonal event,” he says, “no one wants to talk to you until the season begins.” Of course, each successful year has made it easier to get the conversation started. “Nightmare’s” current sponsors include heavyweights like Verizon, Madame Tussauds Wax Museum and Gotham radio station Hot 97. Meyrelles says he’s been approached about adapting “Nightmare” for the screen and has been mulling a traveling version that would operate like a spooky circus. Meanwhile, Haskell is serving as editor-in-chief of Haunternet.com, a recently launched website that calls itself “the world’s largest haunted house directory.” It’s too soon to know if the market will support all this expansion, but Meyrelles says the hunger for horror shouldn’t be underestimated. “The demographics here are incredibly wide,” he notes.