It's an unflinching horror story that takes the best Western tropes ... who may very well be the devil, and a lot of stories about fate. It's one of my favorite movies of all time.
Even back then, "The House of the Devil" had all the horror movie clichés before they were clichés: demons, skeletons, ghosts, witchcraft, sorcery, and a spooky gothic castle. All in just 3 minutes!