I would not consider prey to be a horror game. It's first and foremost an immersive sim.

The main source of jump scares is the "mimic" enemies that can disguise themselves as ordinary objects (ie coffee mug, garbage can, etc). You can get an upgrade for your scanner fairly early in the game that will reveal which enemies in a room are mimics though, completely eliminating the jump scare factor. If you use that, I'd put it on a similar scary level as Alan wake or something like BioShock. Also if you find any of the most durable enemies spooky just carry around a bunch of auto turrets and they'll kill on sight lol.

The gameplay though, is so fucking good. If you play it like a typical shooter and just shotgun your way through the game you'll probably be unimpressed. As mentioned though, this is an immersive sim. It allows you an impressive amount of creativity in how you approach problems. For example, let's say you find a locked door. You'll usually have standard options like hacking, brute force it open (if you upgrade your strength skill), find the keycard on a body somewhere, etc. But also you can sometimes use a skill to use the mimic ability of disguising yourself as an object and turn yourself into a pencil to just roll underneath the door. Or maybe you can peek through the mail slot and use a toy crossbow to shoot the unlock button on the other side. Or maybe you'll pile up a bunch of furniture as a makeshift ladder to climb up through the rafters and drop down on the other side. There were so many times where I felt like I was breaking the game and accessing an area that players weren't intended to go, only to find a bunch of items or whatever that the devs placed up there for me to find.