Hundreds of millions of people around the globe are already devoting larger and larger chunks of time to this alternate reality. Collectively, we spend three billion hours a week gaming. In the United States, where there are 183 million active gamers, videogames took in about $15.5 billion last year. And though a typical gamer plays for just an hour or two a day, there are now more than five million "extreme" gamers in the U.S. who play an average of 45 hours a week. To put this in perspective, the number of hours that gamers world-wide have spent playing "World of Warcraft" alone adds up to 5.93 million years.

via WSJ.com.