Left For Dead 2
Valve's second stab (and bludgeon) at the multiplayer zombie FPS spans five new campaigns in the Southern USA, from Savannah to New Orleans, and promises a stronger narrative arc across them as we get to know the four new characters - a high-school football coach, a female cable news reporter, a mechanic and a conman.
L4D2 has all our old Infected friends, along with a bunch of new ones, including the Charger, whose giant mutated arm is good for knocking you through the air, and the Wandering Witch, who still doesn't like to be disturbed, but doesn't exactly help herself by stumbling about in a daze rather than sitting down out of the way.
New melee weapons include the frying pan, chainsaw and axe (slice legs offs!), and there's also a new semi-auto shotgun and sniper rifle, all of which should help push the rank-and-file Infected into nice new ragdoll deaths, including a new hazmat-wearing model who's resistant to fire.