PopCap Games has acquired Chicago-based game developer Retro64 for an undisclosed sum, the Seattle casual game maker said this morning. The deal will allow PopCap to bring new action and puzzle games into its library of computer game titles. In addition, Retro64's Chicago office has become a PopCap development studio, managed by chief producer Mike Boeh, who was director of technology for Rollingstone.com before founding Retro64. Retro64's arcade style games include Venice, Water Bugs and Platypus.The company takes its name after the Commodore 64 computer, popular in the 1980s, and the fast, simple games created to play on it.