Why does everything need to be explained?

Rating: 7/10 (6 January 2019)

There are these entities that when you see them drive you to suicide. Some people, the movie hints at it being those that are less than sane, act as facilitators for the entity rather than commit suicide. There's a bunch of people holed up and trying to survive. They get into a bunch of situations. It's really great entertainment, tense and a bit jump scary at times. Loved the film, only the ending was a bit of an anti-climax.
I don't get why everything needs to be boxed off and neatly explained for it to warrant a decent rating.