Free Team Fortress 2 turns 20 to 30 percent of players into payers

Show me the mon--wait, scratch that. Valve has already seen it, and co-founder Gabe Newell is interested. During a conference in Seattle, the overseer of hit hardcore game franchises like Portal said that Team Fortress 2--its popular multilplayer shooter that recently went free-to-play--has seen incredible results in how many paying customers it has created.