It should come as no surprise that Left 4 Dead is our Co-Op Game of the Year.  The game exemplified a cooperative experience by simplifying things, and taking the basic need for survival to drive home teamwork.  Solid graphics, great sound, and near infinite replayability all add to this title, but it's the sheer fun you have when playing with friends that make this the easy pick.  Like nearly all of our editors have said - there's nothing else like it out there.  So kudos to Valve, Turtle Rock Studios and everyone involved with Left 4 Dead.  I'm sure we'll be playing it well into 2009!