Among the ten thousand criticisms reserved for the Call of Duty series, one persistent complaint is that the game engine hasn't been changed in forever. According to Treyarch's Mark Lamia, however, Black Ops II doesn't need an updated motor, even in the face of insanely pretty games like Battlefield 3.
"People always ask me, 'Is this a new engine?' I liken it to people who live in an older house that has been remodeled," Lamia told One of Swords. "Just because you’re remodeling the house and it will look new or it will have a new kitchen, you don’t tear out the foundation, or break out some of the framing. You might even go as hardcore as replacing the plumbing, and we will do that sort of thing, as an analogy. It’s a gross simplification, but it’s one way to say that. There’s a lot of good still in that foundation that you wouldn’t get rid of, and we don’t. We look to advance in the areas that support our game design.
"Engines, each time they get touched, they change. The creators alter them; they don’t modify what they don’t need to, and then they alter what they need to. You can’t make a competitive product if you’re not upgrading that engine along the way."
As someone who cares more about what's done with a game's visuals than the visuals themselves, I've never been too hung up on COD's graphics. They're not ugly and they don't affect my enjoyment of the game. That's just me, though.