Keep in mind that a game is a different medium/media than a film. Since it's more personal and interactive than a film it's easier to build tension.
While Alien: Isolation was incredibly tense, I'm not sure I'd call it scary. You knew what was hunting you, you knew what it looked like and you knew what got it's attention. Real fear is best generated by the unknown and what your imagination does with it.
I agree with the unknown, but an Alien in a vent is scary.
It's in the dark, you can't see it, but you know it's there, and it's coming straight for you.
This 'In the vents" made me think of the way the scares in alien and aliens were very much about the use of the sets in the story. In Alien, you're constantly on edge, because you don't know what it looks like, or where it is, and the Alien has tricks up its sleeve.
In Aliens the same goes. First you're in this Hive and the audience is on edge thinking what's this place...? Then they cant use their weapons, the whole colony is cocooned there, then they come out of the walls, then they are trying to escape. It keeps throwing new information at you in an unnerving way AND making use of the space/sets. Then AND MOST IMPORTANTLY when they hold up in the Med labs/compound, the audience is told: We are sealing these access tunnels, then we are using sentry guns and etc... You are always aware, in the audience, of the surroundings and what steps are being taken, and wondering where they will come from etc.
The motion-trackers help too.
Even the part in the med lab where the facehuggers attack. Its a great use of the set. They can't break the glass, BUrke shuts off the monitors, the gun is outside on the table - its such a great detail because it's not just missing, its right there to be seen - they set off the sprinklers... All about the set.
Overall, the use of the space is important. You need great set-pieces. Think about the first time you heard Ripley say "That can't be that's inside the room!" - All of that works because of the information we are given about the compound. In Alien 3 and A:R there is no real use of space. The only part that worked in that scene was the underwater scene because the set and events combined to surprise us. Especially when the exit was covered in that secreted resin. A nice set-piece. In Alien 3 the only decent set-piece was the Bait and chase at the end.
The problem with A3 and AR is the set pieces weren't so great. Prometheus had a few, but they seemed disconnected from each other.