Admission: I’m a bona-fide horror nut. I love it. Can’t get enough. You name it, I’ll watch it: past-their-sell-by-date franchise sequels, grotty Eastern European video nasties, creepy found-footage indies, cliché-ridden teen slashers, and everything in between. So, PS4-exclusive interactive horror Until Dawn is right up my alley.

Duly, last month I sat down with Jez Harris from developer Supermassive Games to pick his brains about the science of scaring poor innocent folk like you and I. He happily obliged, talking me through a few of the strategies the Guildford-based studio is employing to ensure you’ll need to keep a clean change of underwear close at hand when the game hits the shelves later this year.

1. Bring in the experts

“We have Larry Fassenden and Graham Reznick as our script writers,” explains Jez. “They are horror encyclopaedias in human form and have worked on all sorts of acclaimed horror movies, like The Innkeepers and Stakeland.”

He’s not wrong – these two know what they’re doing. If you’re curious and of a hardy disposition – check out The House of the Devil and The Roost too.

2. The element of surprise

“What we’ve tried to do is ensure that if you’re a fan of horror movies it will feel familiar – and that’s absolutely deliberate,” says Jez.

“What we want to do is put you in a playable horror movie. We want to make you feel like you know what’s going on and that you’re in your comfort zone. Then we can yank you out of it extremely hard as the twists and turns play out.”

3. Always have willing test subjects

“One of the things we realized very early on is that once we’ve been scared by something, that scare quickly diminishes every time you play,” Jez explains.

“And of course we play the game an awful lot, so you start questioning whether something is scary, forgetting the fact that it scared the life out of you six months ago. So we do a lot of user testing. We get players in that are completely fresh to the game, so we can check that we’re still making an impact.”

4. Harness the science of fear

“We do a lot of work with galvanic skin response,” Jez continues.

“We have testers strapped into apparatus that monitors their temperature and the level of moisture in their skin. We’ll sit and watch the data as the person plays the game, and if we get a good spike we know we’re doing our jobs right. And if those spikes correlate across a number of separate players then we can be confident we’re on the right track.”

While these poor test subjects help the developers deliver on their promise, Jez – with a sadistic glint in his eye – is happy to acknowledge the team enjoyed a little schadenfreude too.

“We’ve had some great fun seeing the video output of our user testing – guys who are sat there, playing the game peeking through their fingers, not being able to look at the next scene, telling themselves to ‘man up’. We haven’t induced any heart attacks yet, but I think we’re getting close!”

5. Throw out the rulebook

The best horror movies keep the viewer guessing, eschewing cheap scares in favor of atmosphere and the unexpected. And that’s a rule that Supermassive seems keenly aware of.

“We were aware from early on that we didn’t want the game to be an endless stream of jump scares,” Jez insists. “People just become numb to it.”

“To make the horror as effective as possible you need to telegraph in some of the scares and then obscure others, otherwise players get wise to a formula. So a lot of Until Dawn is about the quiet dread of not knowing what’s going to happen next. You might think there’s a jump scare coming any second, and then there’s nothing for five minutes – when you’re not expecting it. It has more impact that way.”

While I love the genre, I’ll freely admit to being a bit of a coward when push comes to shove. No matter how many horror movies I inflict upon myself, and how familiar I become with the genre’s structures and rhythms, I still watch them with the lights on, squirming, with a cushion close at hand. And having spent some time with the game, I’m happy to report that’s exactly how I’ll be enjoying Until Dawn too.

“We’ve seen people at events playing with the full headphone set-up, and they’re literally falling over at what they’re experiencing!” says Jez, when I ask for permission to play the demo build like a lily-livered wet blanket – with the volume down and headphones off.

“What we’re doing here is making a playable horror movie. How you’d sit and watch a horror movie at home is probably how you should play Until Dawn. For me personally, that would definitely be with friends – I wouldn’t want to do it on my own. I’d be too scared!”