Left 4 Dead 2 will be free to download and play in a Steam promo starting today and running all weekend long. I suspect that Halloween-special news will be received as a treat by many, but a trick by others. Valve seems to understand that L4D veterans might not be interested in showing an influx of rookies the co-op zombie shooting ropes, so it's throwing in a little promo incentive in the form of a new achievement: "Good Guy Nick - Plays games with free weekend players and helps them survive a campaign."
Valve announced the promo on the Left 4 Dead blog, encouraging long-time players to welcome "new found friends" and help them survive the zombie apocalypse.
Looking for the free promo? Valve says Left 4 Dead 2 will drop the price tag at roughly 10 a.m. PST.
