Bad news for gamers who were planning on blasting zombies come this Nov. 4th: Valve’s severed undead limbfest has been pushed back until Nov. 20th. Valve has not given an official reason for the game’s two week delay, but we’re guessing that it has something to do with all those other blockbuster titles which will be coming out around the time of Left 4 Dead’s original ship date (see Fallout 3 and Gears of War 2).

Interestingly, this delay places Left 4 Dead’s launch on the same day as Half Life’s 10th birthday. I guess playing one of the most highly anticipated games of the year is as good a way to celebrate as any!