Since its debut in 2009, Minecraft has become one of the bestselling video games of all time, remarkably without guns or blood! More than 91 million people play it every month. But it's more than a Lego-like universe in which players create things; teachers are seeing the benefits of playing Minecraft in their classrooms. David Pogue visited a middle school in Basking Ridge, N.J., and the Minefaire gathering for Minecraft enthusiasts; and talked with YouTube celebrity JeromeASF, for whom Minecraft videos aren’t just a passion, they're a calling.