From the introduction
tremulus is a storytelling game of Lovecraftian horror where you take on the role of a person who has been destined to live an interesting life, one touched by blood and bile, dark revelations and horrible sacrifice. The weight of the world is upon your shoulders as you strive to drive back the darkness threatening to drown it out.
From the back of the book
Want to See Something Really Scary?
We all do. tremulus lets you and your friends make terrifying stories together. No experience necessary. And dice? You only need a pair of regular old six-sided dice, like you find in most family board games. If you've never played any roleplaying games in the past, then this is a great game to start with.
What if I know nothing about Lovecraft?
If you know what scares you or your friends, that knowledge and the guidance found in tremulus will give you more than enough to get going. (It's not homework, but if you haven't read any of HPL's work, go find some. You're in for a real treat.)