From the Kickstarter Blurb:
tremulus is a storytelling RPG where you and your friends get together and create a haunting story in the vein of HP Lovecraft's works.
The rules of tremulus are based on Vincent Baker's Apocalypse World and influenced by elements of Fiasco and FATE. New elements drive the game into more investigative directions, handle sanity loss and madness, and streamlines the role of the Keeper (the game master.)
tremulus is a storytelling game by Reality Blurs, set in a world where the mythos of HP Lovecraft comes to life. Based on the Apocalypse World engine slanted towards the themes of such works, it is different from other forays into this genre in that it works off the uncertainty principle, and the fact that even the Keeper isn't totally aware of everything as it develops as the story is told.