Just like with a real guitar, when you've played Guitar Hero long enough, you start to master the songs. But unlike a real guitar, you're not going to bust out your skills on stage for anyone, because it's still just a game. When you've got friends over, it's always fun to challenge them to a head-to-head match. But what about when you want to have that same kind of fun, but there's no one else around? Well, there's a new mode for that.