I think you can make a broad-daylight horror game that would terrify the player, but it needs to be something subtle, something that throws the player off, and something that hits close to home for a lot of people. Abduction, for instance.

The issue with horror games, and making people scared, is that... people are scared by different things. A spooky camp night in a murder clown factory is one person's biggest fears, and another person's "meh." These change, too, as you grow -- when I was a kid I was afraid of the dark, I was afraid of monsters attacking me from the woods. I'd have nightmares about them. Now? I have nightmares about being late to work and getting fired, or nightmares that I've never received a job in the first place and I'm still languishing in unemployment. That wouldn't make a very good horror game, though.

On jumpscares -- there was a great quote by someone that I sadly can't remember, and therefore can't credit them, but it was "Jumpscares are to horror as tickling is to comedy." Jumpscares rely on a very primal instinct in humans -- we are started by things suddenly rushing at our face -- but I wouldn't necessarily call it horror. I love the FNAF series, but the jumpscares aren't why I like the games.

I think the overall issue you run into with horror games, is as you get older, subtler terror is more appealing, whereas when you're younger, very visceral blood-and-guts-murderer-jumpscares are more likely to scare you. You're going to get one crowd going "That's not scary" no matter what sort of game you make.

Personally though, I think one of the more successful horror games to come out was PT, though I guess that's not really a "game." It's both subtle and in-your-face at the same time. It's not enough to keep me up at night, but I thought it was really good.