The once-hot social gaming company said that Mr. Pincus decided to give up all operational responsibilities, though he will remain Zynga's chairman and largest shareholder. … Founded in 2007, the company became the hottest of a new breed of game start-ups. Before anyone else, Mr. Pincus figured out how to use the exploding growth of Facebook to create games that spread like wildfire across the social network. For a time, Zynga pumped out hit after hit, like