Games have a seemingly supernatural ability to punt my heart into my mouth. Nothing compares, not the slow burn terror of Ridley Scott’s Alien, nor the sickening dread of watching a Dario Argento film. When games press the right buttons, they spark a physical, innate sense of threat, instantly sending the hard-wired fight or flight reflexes in the brain flaring into action. Run. Hide. Survive.

But why are games so good at unsettling us, and how do developers shape their creations to make them as terrifying as possible?

(Above: Amnesia: The Dark Descent)

See related Horror, humour and purgatory: In conversation with BioShock and The Magic Circle developer Jordan Thomas SOMA, BioShock and horror: how games tap into our internal fears Minecraft sonnets: How the worlds of poetry and gaming are coming together Over the next week, I’ll be tackling this question, having spoken to a range of leading game developers and experts about games from Alien: Isolation, SOMA and Amnesia: The Dark Descent to BioShock, Thief and F.E.A.R.

In part one, I’ll be picking apart the building blocks of fear: how sound design and enemy AI go towards terrifying players. Next week, in part two, I’ll be looking at the ways that story and level design are ushering in a new breed of horror game.

The Sound and the (threat of) Fury

Seeing the enemy in a game is rarely the most terrifying part of the encounter. Sound, as every good filmmaker, theatre director and haunted house architect will tell you, is one of the most potent tools for creating a sense of tension.

Thomas Grip, creative director at Frictional Games, is behind titles such as Amnesia: The Dark Descent, the Penumbra series and the recently released SOMA. He spoke to me about how crucial sound design is to the development of both horror games, and computer-generated worlds in general.

“Sounds sound a lot more real than how graphics look,” he said. “It is very easy to see flaws in the art, but a lot harder to hear them. So when you hear a monster it feels a lot more real than actually seeing it.

“Sound is a great way to give the world texture. If you hear the sound of wooden boards creaking above, it emphasises the fact the ceiling is indeed made of wood and it feels a lot more real. The images provide more concrete data for the player, like what sort of space it is, but the sounds are what give that extra spice to make it feel real.”

While the visual environment of a game can provide heaps of information to the player, Grips’ comments suggest that sounds that emanate from the things we can’t see are what open our imaginations to all sorts of horrible possibilities. Even for a medium famed for its visual potential, there is a great deal of power in what isn’t shown – in what’s left for us to imagine.

Personally, I can attest to this; hearing the inhuman cries of the hybrid enemies in System Shock 2 before seeing them always sent a jolt down my nervous system. Likewise, the wet ache of BioShock’s Rapture – its rich symphony of dripping water and creaking architecture – created an unforgettably tense atmosphere, as did the intermittent hum and crackle of the radio in Silent Hill. Hearing something waiting in the dark is so often far scarier than seeing it in the light.

https://youtube.com/watch?v=JdLrooeI3wU

Stealth games – with their atmospheric, generally slow, gameplay – tend to pay specific attention to sound design. The Thief series, while technically not horror titles, have provided some of the most unsettling gaming experiences ever devised. Perhaps the most iconic of these is “Robbing the Cradle” in Thief: Deadly Shadows (or Thief 3), a masterclass in level design spanning a vast building, which, as you learn over the course of your time there, was both an orphanage and an insane asylum at the same time. This ominous environment is perfectly complimented by a haunting sound design.

Jordan Thomas, the man behind Robbing the Cradle, designer on BioShock, director on BioShock 2 and writer on BioShock Infinite (and architect of the superb The Magic Circle) explained what made it so terrifying: “The first half of Robbing the Cradle is a little exotic for a Thief mission in that there are no AI enemies to hunt you. You are just being hunted by sounds. You’re hunted by what you imagine coming after you – the more the environment can suggest than state, the more spare cycles you have to mentally scare yourself. People would imagine whatever they found to be the most menacing.”

(Above: Thief 3)

Letting the player’s imagination run riot is, as Grip and Thomas suggest, one way of approaching the monsters in a game. The most terrifying adversary is what we build with our own minds – the nagging feeling that something unseen is lurking just behind us. Our worst nightmares lurking close by.

But what about the thing that actually is coming after you?

Intelligent Monsters

The first time I played Alien: Isolation I was with a group of friends. “Look at that bony prat,” I shouted, pointing at the gangly xenomorph while my friend cowered behind a box. We laughed. My friend died. Later, alone in the dark, I clasped the controller with what I can only describe as religious penance. The sound of laughter gone. The beep of my sensor told me the alien was close. I pelted across the room to an air vent and there it was, toying with me. What scared me wasn’t the look of the alien, but how intelligent it was. I was being hunted.

“Alien: Isolation is one game that completely nails the use of AI for horror,” Michael Cook explained. Cook is an AI expert and senior research fellow at Falmouth University, and has spent several years working on automated game design, including a project to develop an AI system that can intelligently design its own videogames. He also runs PROCJAM, a game jam focused on procedural generation. Convincing the player that the AI is better than it actually is, he explained to me, is a crucial element of what makes Alien: Isolation so terrifying.

(Above: Alien: Isolation)

“Creative Assembly understood how to use level and sound design to support an AI character like the alien, to cover up its weaknesses. If the AI does something stupid, it breaks the horror illusion and the enemy isn’t scary any more. Things like allowing the Alien to escape into vents and designing levels with blind corners and obstructions means you can keep the tension high without forcing the Alien to expose itself too much.”

Artificial intelligence, much like real intelligence, is convincing until the person wielding it does something stupid. When the alien appears to lie in wait or hunt you through spaceship corridors, it’s easy to convince yourself that you’re at the mercy of a perceptive monster. When it circles in the same route and gets stuck on doorways – less so.

https://youtube.com/watch?v=uqmlNjPWNXA

Jordan Thomas told me that, in terms of Thief 3, the tactic with enemies in Robbing the Cradle was similarly angled towards the ethos of less is more, an inspiration drawn also in part from Spielberg’s Jaws: “I definitely knew that if you showed too much of the shark it would lose all of its menace,” he tells me. “It now cracks me up that Spielberg said that he wanted to show more of the shark but just couldn’t afford it.”

It turns out, though, that there’s a useful side-effect of making your antagonist a shark or an alien. According to Michael Cook, choosing to make the enemy of the game a non-human monster is actually a clever way to cover up potential flaws in its intelligence.

“We’re too familiar with human intelligence, which makes it easy for us to spot mistakes and slip-ups by the AI,” he said. “But animal intelligence has this unknowable quality to it – we see it in games like Alien: Isolation or Amnesia – where we can’t always rely on it to be predictable or understandable. I think this kind of leeway is really important for developers, because it allows them to bend the rules a bit – we can be terrified by how clever a monster is, or how impulsive and aggressive.”

Playing against an animal or monster, we make unconscious concessions about its intelligence. As soon as you have an avatar that looks like a human, we expect more. What if you can convince your player that there is more? Jeff Orkin, AI developer behind the 2005 title F.E.A.R. reassured me that humans can be scary after all.

“Animals might have heightened abilities to see or hear, compared to humans, and might have greater physical strength, but they’re not going to try to second guess or outsmart you,” he said. “When you see a human threat, and that threat evades you into the shadows, what is he going to do next?”

(Above: F.E.A.R.)

Orkin tells me that, although F.E.A.R. is still lauded for its AI, many of the reasons players were unnerved by the intelligence of the enemies were down to clever sound design: “We took every situation where an NPC would normally say something – crying out in pain, detecting a threat, losing track of a threat, retreating – and replaced the “bark” or monologue with a dialogue between multiple NPCs. For example, instead of crying out in pain when an NPC gets shot, we would have another NPC shout “Are you alright?” and the guy who got shot would reply “I’m hit!”.”

Fear of the machine

What happens when you go further than animal and human intelligence? In System Shock 2, a large portion of horror comes from the omnipresent threat of SHODAN, the rogue AI in control of the Von Braun. Having SHODAN aware of your every move layers your actions in the game with an added sense of paranoia, but as Cook told me, while superhuman AI makes a great antagonist, a truly intelligent AI would be incredibly frustrating to play against.

(Above: System Shock 2 – warning SPOILERS)

“It’s really hard to convey extreme intelligence while also allowing the player to stay alive long enough to be scared,” he said. “We could imagine an incredible intelligent creature that the player can’t outwit, and that might be completely terrifying, but if there’s no way to eventually win and overcome it then the effect probably wears off quite quickly.”

While horror movies get a lot of scares by showing how unstoppable a creature is, it’s a much harder trick to pull off in games without alienating the player. Cook explained to me that game AI is more like a pantomime villain than a real monster, where its aim is to play along with you to tease out the most dramatic scenes rather than flat out kill you. If an game AI really did let go, you’d be dead in an instant.

That, in itself, is quite a terrifying idea to consider.

Smart AI can be scary, but the illusion of intelligence isn’t the only way to unsettle players. Next week, in part two, I’ll be looking at how games can go beyond jump scares, to make us scared our ourselves. I’ll be talking to Jordan Thomas about BioShock, Tom Jubert and Thomas Grip about Penumbra and Soma.