If you’re a fan of 3-D shooters, act quick: Valve’s fantastic 2009 zombie survival game Left 4 Dead 2 ($20) is free right now! Why rush? Because after 1:00 PM ET today, December 26, the game jumps back up to its normal level. Free games are good, and good free games are even better. You’ll rarely find such a great deal on a high quality title like this.
