The teaming up of Resident Evil 6 characters with Left 4 Dead 2 gameplay has begun, bringing reskins of protagonists in both games that feature their pals from the opposing franchise. Ever wanted to take Coach or Ellis into the world of Umbrella Corporations and horrific Milla Jovavich sequels? Then now you'll be able to. Similarly, zombies from L4D2 like the mini-tank and Witch can now show up mid game.
Of course it wouldn't be fair if this transition was just one way. Anyone running and gunning in Left 4 Dead 2 now has the option of doing so against newly reskinned super zombies, including the Ogroman, Lepotista and Napad - replacing the Charger, Boomer and Tank respectively.