Angst (1983)

Guy gets out of prison. Kills a family. Goes back.

It's not got much of a plot but it's filmed in an intense unnerving way. Most of the movie is the guy working over a family while his internal monologue plays describing how he is feeling and so on. There are maybe 5 full minutes of dialogue in the whole thing.

I liked it. It was apparently widely censored probably because of the extremely grim general tone of the thing as there is hardly any graphic violence. But a lot of sadistic violence.

This movie is difficult to find and I think that is largely due to it's title being used for other movies in other languages.