Kamurai
Really good watch, would watch again, and can recommend.
Brittany Snow is great in this, she really does a top notch embodying the terror of her character while still being a strong female lead. There are also other actors in this.
Honestly, Idris Elba and Johnathon Schaech carry a fair portion of the movie.
It does do something fun when it follows the villain as if he is one of the protagonists. It helps that some of the teens are awful, you can almost root for him as he progresses.
It is hard to talk about without spoilers, but I can safely say that they manage to both follow him and kept the audience guessing about what the villain is going to do next.