Starting today, October 25th 2012, you’ll be able to play Left 4 Dead 2 for free on Steam this whole weekend! If you have not checked out this co-op horror masterpiece, now is the perfect time to do so. You can even score a new achievement created just for this weekend! “Good Guy Nick” is an achievement that can be scored by helping a new player survive a campaign. There is even an official game group chat where you can chat with Developers from 10a to 6p PST on Saturday.