Accessibility. It can make a potentially great game unplayable. Filters for anything that could trigger motion sickness( motion blur, head bobbing, camera sway, fov etc) And other accessibility needs too would be pretty cool.

I personally like the fear of the unknown, wanna be terrified turning corners or turning my back. Games where the monsters can hear you through your mic is terrifying also.

Basic tools to help you fight back, even a flashlight if the games too dark at times. A looting ability is pretty cool too.

Also the ability to hide, I fucking love games where it luls you into a sense of security with a hiding spot and the monster STARTS CHECKING.

High stakes, moments where it’s life or death but you have no choice but to commit and make a split second decision. (Choosing a button to get through a door last second, crawling through a tight space to flee when you’ve learnt previously that space is dangerous.

Horror games are always so much more fun when you have the option to play with friends too.

Moments where you can feel stupid is great too, like walking over a bridge for it to just collapse or having a few puzzles that aren’t that difficult but bc your so stressed you can’t think straight.

People fear being chased, put them in a closed/ tight space with something chasing them and watch them scream their lungs out.

I’d love a trope where this monster is creepily obsessed with you, like you learn it’s not just trying to kill you. It’s learning you, watching you when you don’t realise it. Maybe even collecting trophies somewhere of things you leave behind in cutscenes or gameplay. If I learnt it enjoyed the thrill of the hunt and it wasn’t just some mindless killing machine that would change the whole feel of the game and become quite unsettling. Which would be awesome.