In April 2008, Retro saw the departure of three key developers, designer Mark Pacini, art director Todd Keller, and principal technology engineer Jack Mathews, who went on to form their own company, Armature Studio. Around the same time, Shigeru Miyamoto asked fellow producer Kensuke Tanabe to recommend a studio that could develop a new "Donkey Kong" game, and Tanabe recommended Retro. Kelbaugh had worked on the "Donkey Kong Country" series during his years at Nintendo of America, and had interest in continuing with the franchise. Retro accepted the task, and thus started development of "Donkey Kong Country Returns". Similar to "New Super Mario Bros.", the game was developed with the intention to invoke nostalgic feelings in the player with its art style and sound, while trying to provide them with new gameplay experiences. "Returns" employs fully polygonal 3D graphics with three times the amount of textures and polygons that "Corruption" offered, and over the course of six months, two thirds of the game's tools and engine had to be rewritten by the programmers. Development accelerated at the outset of 2010, and the project was just "beginning to cohere as a game" around the time of E3, when it was officially announced to the press. Although the game was set for release in autumn that year, the team still had 70 levels to create or refine.