Why this movie sucked

It was actually decently done in terms of production values and acting. (Although the Alex character was incredibly stupid, irrational, and annoying.)

But the failure to provide any explanation - or hint of explanation -- whatsoever made this a total loser. I had no idea at the end why I waited until the end.

Movies like this demand/require at least some sort of explanation for the unusual events. Someone tell the writer/director that.