Maybe L4D2

It took me exactly 5 hours to finish the campaign... it was great while it lasted, but the abrupt ending ( I don't even think it's worthy of being called a "cliffhanger"... it's closer to The Sopranos' series ending where you're like "WTF that's it?!?") put a sour taste in my mouth, because I know now that MW3 is a given and it will probably be just as short of a campaign.

The co-op mode is a nice extention of the single player though, very challenging... and I'm loving the MP with the custom kill streaks... although I have ran into the occasional "hit detection issues" that some others have.

I'm just glad they got rid of Juggernaut altogether... and even better, Martyrdom is now a "death streak" perk, where you are able to use it only after dying 4 times in a row without a kill! That's the one thing that pissed me off most about COD4's MP, was the assholes who suck at the game and would just rush you while you're cornered or in a tight spot, and you have no chance of escaping the dropped grenade since it explodes after literally 1 second of being dropped.

The respawn system still seems broken. I go into an area where literally 4 enemies pop up on my screen...