This British gem came out of nowhere back in 2011 and blew me away. A group of rough kids in a housing block in England form the only line of defense between their homes and a vicious group of alien invaders. This one almost leans so heavily towards sci-fi action that it barely rates as horror but space monsters qualify it. This was the breakout movie of John Boyega (from Star Wars: The Force Awakens) and the first theatrical movie directed by Joe Cornish (who helped write the Ant-Man screenplay).
The main trick of the movie is getting us to pull for a gang full of hooligans who terrorize their block until it is time to protect it. In a way, it is about unification due to outside threat but the real accomplishment is making these thugs the heroes of the movie that you end up pulling for. Unlike similar child endangerment flick Super 8, not every kid makes it out of this one. This is a dark movie with some very funny bits (Nick Frost cameos as a drug dealer). If you like alien action and haven't seen this, I would recommend it.