Horror games are a genre I personally don't like because they're about atmosphere over game mechanics. And that's fine if all you want is the atmosphere. But I think if you reduce the game design down, a lot of them are very under-ambitious and I for one would like to see more innovation out of the genre.
From the games I've seen let's plays of (a lot, it's a popular let's play genre), there's a few basic gameplay sequences:
-run between cover only when it's safe, but the dangerous periods make a spooky noise and light
-run from the monster which is very scary, if you slow down you get caught
-hallway With Jumpscare™
-hide in a closet while the monster patrols, it will probably sniff at the closet to feign finding you before walking past
-solve a puzzle But It's Spooky
Most of these... Can't really be iterated on? You can mix and match them in but then when every horror game mixes and matches all these same tropes in, the genre becomes a milquetoast blend. There's no depth.
I'm someone who doesn't get my gratification in games from the ambiance and story so I get that these games are not aimed at me but I can't help but feel there is something missing from this genre critically at the game design level.
And to play devil's advocate against myself, I can see similar arguments being leveraged against my own favored genre of 2D fighters from the outside. Without nuanced knowledge of what makes them tick, truly what is the difference between a Street Fighter and a Mortal Kombat besides set dressing?
But a 2D fighter has complex mechanical parts. Even if you view the different characters as just set dressing, you have to admit, Ryu plays fundamentally differently from Scorpion and when the goal of the game is to compete, that's going to radically change your experience. And that's before going into more nuanced system differences that you'd have to know the games to understand.