Until the surprise was revealed at its premiere at Comic-Con in July, hardly anyone knew the horror movie initially billed as “The Woods” actually was “Blair Witch,” the second sequel to the groundbreaking “The Blair Witch Project,” released back in 1999.

“The way you keep a secret is you just don’t talk to anybody about it,” said writer Simon Barrett very succinctly. “Lionsgate told us at the beginning of the project they thought it would be a cool idea to imitate the surprise of the original film back in 1999, which obviously faced a very different level of internet scrutiny than modern films do. So, the studio really wanted to surprise people, and we were very excited about that. That’s exactly what we want as viewers of films — to not know everything about what’s going to happen when we are going in to see a film.

“Of course, we didn’t realize going into this project that we were not going to be talking about if for like three-and-a-half years!”

Adam Wingard, director of “Blair Witch” (now in theaters), noted a number of things that secrecy pledge required. “We had to do some unorthodox things. Simon had to adopt a fake draft of the script. I don’t even know who all had the normal, real draft, but it wasn’t very many people — mainly just the cast members and a few others.

“It also presented other unusual challenges. When you went out to hire crew members, you couldn’t tell them the movie they would be working on. We’d say things like, ‘This will sound like a ‘Blair Witch’ ripoff, but trust us, it’s going to be good!’

“So, you know, the secrecy thing was always looming overhead.”

That discussion of the secrecy aspect reminded Barrett, that “even our casting directors didn’t know the film we were making. So our cast only found out what film they were actually making — after they agreed to be in the movie.”

Asked if the success of the first film put pressure on them to step it up as filmmakers with this new movie, Wingard said the pressure was the “desire to maintain the realism the first film had. But we knew we actually were making a different type of movie. Ultimately, we’re taking the ‘Blair Witch Project’ kind of universe and we’re creating a roller coaster ride within that. We’re throwing audiences into this very immersive [point-of-view] experience. It’s meant to be a thrill ride, which is a very different take than from the first film.”

The director noted that the feeling of what he called “authenticity” in the original ’99 movie was key — “and actually the thing that makes it stand out as a unique piece of filmmaking. We were always trying to balance the cinematic approach with the found footage kind of thing, and find the balance between reality and just exciting moviemaking.”

Since making horror is what this writing and directing duo like to do — as seen in their projects including “The Guest,” “V/H/S” and “You’re Next” — it seemed fair to get their take on what makes for really good, scary film.

“First, you want to do something that hasn’t been done before. A good example would be the films of James Wan, who is kind of the master of horror right now,” said Barrett about the creator of such horror epics as “Saw,” “The Conjuring” and “Insidious.”

“Secondly, I think a truly scary film stimulates your imagination. It’s not just about scaring them in the theater — though I’m pleased if we do that. No, it’s more about scaring them later that night, when they wonder if maybe they heard a footstep in the house or maybe they saw something in a doorway.”

Wingard nodded about that, and added, “That’s what made the original ‘Blair Witch Project’ so successful — because it raised more questions than it answered, and that’s what kept you thinking about it.

“We were conscious about that here too. We needed to show more than you saw in the original film, but ultimately everybody needs to be able to give it their own interpretation.”