Valve's annual Dota 2 tournament -- The International -- is now one of world's biggest sporting events. Thanks to the Valve's most excellent shepherding of both the game and the 5-versus-5 MOBA genre, an ingenious crowdfunding scheme, and the continuing growth of spectator esports, The International now has a total prize fund of over $6 million. The winning team will take home somewhere in the region of $3 million. To put that into perspective, that's more than all but the top sports professionals take home in a year. How did Dota 2, which only left beta testing last year, become one of the world's biggest sports in the world?