A lot of RPGs are rather high fantasy in nature. But what if you want to bring more creepy horror elements into it? Well, things like The Book of Gaub can help. it's a collection of spells you can add to your games. But also, it's got short stories to help set the mood of strange, grotesque, and horrific elements for your games. The book is up on Kickstarter now.
From the campaign:
The Book of Gaub is a RPG supplement and anthology of creepy magic and micro-fiction, fit for all game systems and tailored to retro/old school D&D in the style of Wonder & Wickedness. Written by seven authors, their concerted effort fleshes out the Seven Fingers of the Hand of Gaub, manifest through the filigrees of cobwebs and nails, false memories, and nightmares you want to forget.
Aside from its core content - 49 spells and small tales - the Book also includes 100 terrible Catastrophes to invoke when its vile magic goes awry. 20 Monsters are bound in the book as well, together with insidious rituals to turn them to your gain. With some of the 49 bizarre paraphernalia in hand, you may begin your descent to the place where fear lies.
The Book of Gaub book takes inspiration from "floorboard and cobweb" horror; touchstones of this are The Babadook, Scary Stories To Tell In The Dark, Stephen King's works like Misery and The Shining, and so on.
The campaign is really close to its funding goal with 29 days left to go.