From Valve (the creators of Counter-Strike, Half-Life and more) comes Left 4 Dead, a co-op action horror game for the PC that casts up to four players in an epic struggle for survival against swarming zombie hordes and terrifying mutant monsters. Set in the immediate aftermath of the zombie apocalypse, L4D's survival co-op mode lets you blast a path through the infected in four unique "movies," guiding your survivors across the rooftops of an abandoned metropolis, through rural ghost towns an...