There is a difference between fear, and anxiety/stress, fear can be associated with the unknown, in a jumpscare using game, you're anxious because you're waiting for the scare you know is coming. Problem with FNAF, I have never played it by the way, but it uses this as artificial horror, yet there is no horror, at the end of the day, it's just a robot screaming at you in most cases in those games. It feeds your anxiety by employing management of resources, that if you run out you're usually going to die, and keeping an eye on roving anamatronics, you see exactly what you're supposed to be afraid of in most of their cases, there is no fear of the unknown when what is hunting you is right on the screen staring into your security camera.
See, horror games that actually scare, usually are heavy in these two things, environment, and darkness. If the environment is stripped to essentials or lacks anything to distract you or add to your current state, and you can literally see the thing that is hunting you, then that takes away from it, stress isn't fear, it's like knowing you're getting fired, it's going to happen, but you can't change that, so you just have to ride it out, that's how you beat a FNAF game, you ride it out and ignore the jumpscares, just see them as a game over and not a shrinking monster in your face. It's cheep. You buy a horror game, instead you end up with resource management, running from what you know is going to show up and announces it's presence to you, or like when you are about to get a vaccine, you know the pain is coming, and that makes it worse. Really I have a theory of why FNAF is so popular, it involves the adrenaline making you want to do it again (maybe like a drug?) drawing the player in, and then the game's lore cementing you playing the game for the story. Plus for some reason the internet likes to see others suffer on youtube playing these kind of games.
Seriously, I played Spooky's Jumpscare mansion, (Do, not, play.) and it has monsters chasing you, with ones based of Silent Hill, Majora's Mask Ben Drowned creepy pasta, Resident Evil, Dead Space, but they all have the same thing in common, no air of mystery to this; if they touch you, it ain't good. Some chase you different than others and some distort the screen when present, but it isn't fear, you know if you just run to the door and get through the next series of rooms, it'll be gone and your health will restore on it's own, you know exactly what every one of them will do to you the instant you let one touch you, fear can grow with the unknown, (thus why the dark can be so scary to a child) but knowing exactly what you're dealing with...Take's the power away from them, and destroys it, not giving it to anything, not the monster in those games, not an in-game version of satan in another, they have no power but what you give them yourself, and when you know what to expect from them, you give them none.
Was that weird near the end there? But seriously, do not play that one I mentioned, there are cardboard cutouts of stuff that will pop out from the walls and make usually loud noises. And you get stressed out just waiting for the next one to happen.
SCP containment breach is different, it has actual fear between encounters because you don't know what horror will come at you next, but as soon as you know their formulas, when one is encountered, it becomes just an anxious quest to get to the next area. Don't break eye contact, don't run unless you need to, lure it through the electric thing, don't use any of the items that are actually SCP subjects, ever. etc. Also, don't play this one either.