The Amnesia Collection is currently free to pick up with no strings attached via Humble Bundle.
Amnesia: The Dark Descent at this point I think it is safe to say is a horror classic in games. The title is often one of the first people think to when they think about modern horror games. It came at just that time when YouTubers and influencers were really starting to grab purchase as mainstream personalities, and since it featured a lot, it cemented its spot. That, mixed with it being properly good have made sure the title has remained a household name in the gaming parts.
If you've never had the pleasure of playing the game, or its worthy, if not bizarre sequel, A Machine for Pigs, you've got no excuse now. If you act fast, you can pick up a free copy of The Amnesia Collection from Humble Bundle. The offer is only good for about a day as of writing (26 January, 2018), so do be swift about it. All you'll need to do is get a Humble account, and you'll then receive a code to activate on Steam. Easy.
The games are beginning to feel a little dated now, but graphical powerhouses are not necessarily what you usually find in horror games. The atmosphere and bizarre mechanics are what will drive you through here. As I said, don't sleep on A Machine for Pigs either. While perhaps a little less scary, it sports a really neat story and some utterly bananas moments. Neither are too long either, so you could certainly enjoy them over a weekend or so. I say enjoy, but of course, I do mean, be generally put on edge and have a few things jump out at you. Fun!