Mark Pincus creates an empire with games designed for Facebook

Every day, some 13 million Facebook users tend to their virtual farms, sowing and reaping crops, buying and raising livestock, in FarmVille. Twenty million build virtual cities with CityVille, 5 million pioneer the West with FrontierVille and 2 million fight Mafia Wars, ordering “hits” on each other and building their “families.”They are playing games created and owned by Zynga, a company ...