The Legend of Hell House. This was a European release from 1973. Based on Richard Matheson's novel, the film is a textbook example of old school horror. What is seen is incidental and what is implied is ten times more unsettling. There is some ghoulishscenes but you couldn't call it a precursor to anything slasher related. No that honor belongs toTexas Chainsaw Massacre. This is how horror movies were before they discovered idiotic swearing, raw sex and gore.