Subscribers: 11.5 million
While “WoW” wasn’t the first massively multiplayer game, it took the category to new heights. Players pay a monthly fee of roughly $15 to play. And Blizzard keeps ‘em hooked with semi-regular expansion packs, the newest of which is due later this year.
It’s not the largest in terms of subscribers, but it’s by far the biggest in terms of revenue.