The apparently very generous and talented people over at Bit Golem have let loose a free horror adventure on Steam, an adaptation of the short story Dagon by H.P. Lovecraft. It's a game that takes place somewhere inside the morphine-addled mind of a former ship's officer, and in that way it's very much the "100% faithful adaptation of the original story" that it claims to be. Dagon takes about 30 minutes to complete.
Dagon is completely free on Steam. So you can just go get it. It'll update with VR support in October of this year.
Bit Golem is a Polish indie studio working on their first game, the fishing and investigation thriller Tales of Herring Lake. If you decide you like Dagon, there's a $5 DLC with audiobook and ebook to support the developers.
I'm a noted cosmic horror game skeptic, and I'm never surprised when a game with the theme is bad. I am surprised when they are good. Dagon strikes a nice balance: It's a point-and-click adventure, so it's more walking you through an interactive story rather than offering up a narrative in which you are a fundamental participant. That's a great step of remove for the genre. But if it interests you, well, go give it a shot. It's free.
Correction: A previous version of this article stated that Dagon was only playable with controllers. This is displayed on the Steam store, but is a bug. Dagon is playable with mouse and keyboard or controllers.