Call of Juarez. This game switches between the good and the bad character. as the good guy, i'm trying to run from the bad guy, and as the bad one, i'm hunting the good guy. Quite a different experience from everything i've played so far. Right now i'm entering a mine with the bad guy, the very same mine the good character escaped right before this chapter, so now, as the badass, i'm going to have to shoot my way through here, so i can continue the persuit. I'm really curious where this story is going.
For those who never heard of it, it's a first person shooter, in Western settings.
http://www.coj-game.com/