Hello! Most of my favorite "underrated" horror movies either aren't that underrated ("Spider Baby," "The Face of Another") or you've already featured them ("I Start Counting")…
But the 2012 indie film "Resolution" (Currently available on Netflix Streaming) really moved me. The basic idea is that a man receives a disturbing video from his meth-addicted former best friend, and he heads out to the friend's remote hideout with a terrible, terrible plan to rescue him from addiction.
It's a fun genre mash-up with an implied attack on the audience, like "Cabin in the Woods"; it's got a good shift of balance as you start to wonder which friend is really crazier; the friendship is palpable, the dialogue is really funny, and the ending is a good sharp twist. Definitely more eerie or thought-provokingly disturbing than straight-up scary, but I loved it.
I wrote a somewhat longer review HERE.
All best–love KT & have found lots of great movies through you all,