In 2009, Valve launched the “Dude, Where’s My Thumb?” contest, challenging fans to submit photos of themselves standing in front of a Left 4 Dead billboard. Th

In 2009, Valve launched the “Dude, Where’s My Thumb?” contest, challenging fans to submit photos of themselves standing in front of a Left 4 Dead billboard. The 25 most creative submissions were personally chosen by Gabe Newell, with each winner receiving a free copy of the game. The overall contes…