participating retailers) now have exclusive access to the momentous event they said would never happen. For the first time in history, two separate Valve universes collide. That’s right: it's a Left 4 Dead/Team Fortress crossover! This is not fan fiction! This is not a dream sequence! The characters from Team Fortress 2 will team-up with Bill's hat from Left 4 Dead 1! And lest you think this is just some marketing gimmick, here's the intricate back-story justifying it: while conducting ...