Dagon is originally a short story by the creator of the eldritch horror genre, H.P. Lovecraft. This version is a free game on Steam that converts his short story into a visual novel. A narrator reads through the tale while you experience the visuals and landscapes described in the story. You can look around you (and it supports VR too!) but you can't walk and explore. You're stuck in place and only move on as you advance the story.
Throughout the game, you can find hidden bits of trivia, which dive deeper into topics surrounding H.P. Lovecraft's life, the story itself, or other bits of background lore to help you understand the time period in which this story was written.
H.P. Lovecraft himself was terrified of the ocean and all aquatic life, ever since he was two years old; although he has no idea what event may have instilled that fear within him. However, he took that fear and translated it into a new genre of unknowable and incomprehensible horror that defied the rules for standard storytelling of the time. As someone who is also afraid of any body of water in which I can't see the bottom, I totally get it.
Dagon is a tale about a sailor who escapes from enemy capture on the high seas by slipping out in a small rowboat in the night. But when he awakes the next morning, he is no longer on the ocean, as a muddy land mass has risen above the ocean level, stranding him along with all sorts of hidden creatures from the deep.
He sees a peak in the distance and spends the next day and night journeying toward it, only to discover on the other side, a giant monolith illuminated in the moonlight, engraved with pictograms of horrifying creatures. But then a creature stirs from deep within a pool at its base...
As a narrative short story, this game will only take you maybe 30 mins or less to play through. But it's fun to search through each area for trivia to collect. There are 20 bits of trivia to find scattered throughout the core game.
The base game is free on Steam, but there are two separate short story DLCs you can buy for a few bucks each. The first is The Little Glass Bottle, a short story H.P. Lovecraft wrote when he was seven years old! It's a cute tale about treasure hunting in the ocean that has no horror elements in it.
The second story is The Railway Horror, which was a nightmare H.P. Lovecraft experienced and wrote about to a friend of his. Both stories have eight bits of trivia each, giving you further background into Lovecraft's life and works.
Oh, I love this game! Really short and easy, and the narrator is fantastic. But I might be a little bias, since Dagon is my favorite in the Cthulhu Mythos, haha.