The best new co-op games are those that do something a bit different, offering more than a single-player experience with another player thoughtlessly tacked on. These multiplayer games account for groups of friends all wanting their own role, with a shared goal in sight and plenty of chaos on the path to getting there. Whether you prefer a chilled out co-op experience or something a bit more frenzied, the last six months have been rich with new co-op titles for…