The Endless is one of those types of movies you can't really talk about because pretty much anything you focus on will spoil the movie for others in some way. I can say that while it's classified as sci-fi, it's also a family drama of two brothers. And it's very interesting as both those genres, perhaps a little too complex for the average viewer though. Nobody is famous in this, but it's well-reviewed (94% at rotten tomatoes) and was selected to be part of the Tribeca Film Festival.
Trailer for The Endless: https://www.youtube.com/watch?v=Ur8UgpvRPXU
I've been thinking about watching this for ages! I will take this as encouragement and get to it fairly soon!