Regarding immersion, do you think it’s of any value at all, or just minimal value? Surely you must believe a horror game at least requires some level of immersion, to scare the player.
I mean, it’s not just that I don’t think it’s of value. I think all the things that people generally associate with immersion are valuable in some way. I don’t think it’s a real thing in of itself. https://critpoints.wordpress.com/2016/09/04/immersion-is-fake-and-a-menace/
I think that what makes this stuff scary is largely the rules governing it. Poor visibility, a feeling of helplessness, a threat that will destroy you at your back, coming from unexpected directions, not knowing if you’re safe or not. To that end, I think you could replace the monster with something totally stupid and get largely the same effect. Much like someone scaring you in real life in a casual context with no established atmosphere. So the game is no longer very realistic or believable (ie. immersive), but it’s scary none-the-less.
Of course, you might be defining immersion here as “engagement” or “engrossment”, which not all people do, so none of the above might have any relevance to you. You might think, “so what if it looks bad? They’re still involved in it.” Immersion is usually associated more with a belief in the fiction. Yes, engrossment or engagement is required for horror, but they’re not exclusively what immersion is typically regarded as. Though some people take immersion as just those things because everyone means something different when they say immersion, and immersion isn’t real, so you can’t point to a real thing to make a solidified unambiguous definition for immersion.
Basically, in short: Immersion doesn’t need to be real for horror to be real. Not all the factors associated with immersion are necessary for horror.