Card Hunter is featuring in Kongregate sweepstakes for the next two weeks. If you play the game through Kongregate you can win Nexus tablets and Pound-O-Dice prizes! http://www.kongregate.com/pages/card-hunter-sweepstakes?haref=FR_CH_Sweeps_110615
To answer the question that always come up: Greenfang is the introductory mission at the very beginning. If you've already beaten it, you just need to start another adventure to get Kong to count it.
Can't help but notice the hundreds of players now in the Kongregate Card Hunter chat rooms. Most of them mentioned they were enjoying the game.