HappySqurriel on 04 January 2013
Based on the pace Nintendo had set with the Wii in 2007, 2009, and 2010, Nintendo published far less games in 2011 and 2012 (probably) because they were working on Wii U projects. While we know some of these projects, there are (potentially) several teams that have been working on games for roughly 2 years that haven't been announced.
