I recently played through Outlast: Whistleblower in its entirety for my YouTube channel. I was a huge fan of the main game, and to this day I consider it one of the best horror games ever made.
The atmosphere is only rivaled by a couple games, Alien: Isolation and the original Dead Space. Not having any weapons means you have to work your way through the environments carefully, which raises tension and makes every little jump scare that much more alarming.
The full playlist is at the bottom of this post, and if you like it be sure to check out some of my other videos! I have some great stuff coming up for Halloween that you won't want to miss.