Zynga Inc. game designer Michael McCormick is departing to become director of game design at Idle Games Inc.

McCormick, who has more than 20 years of experience in the industry, had been the lead designer on Zynga’s popular “CityVille,” San Francisco-based Idle Games said Tuesday in a statement.

“To say that Idle Games is doing new things in the social space is an understatement, and I couldn’t be more excited to join the team,” McCormick said in the statement.

Zynga, the online-game company that sold shares to the public in December, is the biggest developer of games on Facebook Inc., the world’s largest social-networking service.