COD7 Black Ops, came out in late November and believe it or not I've heard of guys who've managed to complete all the levels in just a few hours. For someone who's not that experienced in the game, that seems incredible.
The game comes at you from lots of levels and you need to be able to take in a LOT of information quickly or you'll find the screen turning red fast. You need to be gathering intelligence, picking up weapons, selecting them, firing them and all the time making sure you don't get taken out. When you're new to it like I am, just getting the hang of crouching down and running seems a lot to take in without all the other stuff going on around you.
So far the game has come in for a bit of criticism from hard core players but if you've not played it before or you've only got to a certain level there's plenty here to keep you occupied for hours on end. It's easy to get carried away and forget to sleep but the satisfaction of getting through to the next level or working out why you can't actually run through a wall even though that's where the arrow is telling you to go, is cool.