Well, sorry I've been gone so long. I recently got Dead Space 2, the sequel to the game that really got me started on writing horror. More than being a fun, scary-as-hell game, I find that dissecting the game is actually very worthwhile for understanding it works. Well, why it scares, and applying that to writing.
1. Force People to Pay Attention to Detail
Dead Space isn't an especially easy game, which is where we get the 'survival' part of survival-horror. You're an engineer with a motley assembly of mining equipment taking on hordes of mutant zombies that require dismemberment due to the their distributed nervous system. Since this series is set on space stations/ships, there's a lot of fans and ductwork around so people can breathe and whatnot. Of course, this is also a popular avenue for the smaller zombies (children, babies, skinnier ones) to travel in. It doesn't take long before you start regarding every fan and ceiling duct with suspicion on principle. This isn't helped by the spectacular audio, which features everything from muffled speech to skittering sounds and taps that could be either an off-time fan, or a monstrosity lying in wait. Any sound could be a warning- there are plenty of enemies, some who sneak, some who flank, some who howl to summon others. At least two kinds actively communicate with other zombies.
Speaking of dismemberment, the game also punishes you for not paying attention to detail by having some of the wounded monsters lie doggo once wounded, or simply when you arrive. Other humans have been fighting them as well, so you never know if a dead one you roll up up on is REALLY dead. You learn to check carefully, since there isn't exactly a dearth of supplies around. You learn to be careful, so I'm going to try to figure out a way to work that into my story.
2. Familiarity Breeds Horror
Necromorphs (the primary antagonists in Dead Space) aren't scary because they have claws or teeth or are particularly murderous. They're scary because they're familiar. You can tell that they were human at some point. Their heads are largely intact, minus lower jaws. vestigial arms hang from their fronts. They wear clothing. The smaller ones look like deformed children. Some look like skeletonized dogs. You can tell what they were by looking at them.
Likewise, even on a starship, an elementary school and hospital look like they do today. Washbasins. Beds. Flowers. There's one particular scene where you walk into the lobby of the doctor's office, and it looks just like one. There are balloons. A gift shop soaked in blood. Discarded magazines and cards. An abandoned wheelchair. It could be any doctor's office anywhere, minus the body parts and blood.
Those are the two big lessons I took away so far. Suspect everything, and the more familiar and comforting something seems, the easier it is to subvert that feeling.