Back in 2011, I published a platformer game on Xbox 360’s Indie Games channel. Angry Zombie Ninja Cats was built on top of the Platformer Starter Kit, and was put together over the course of 2 weeks. It also helped me assemble the XNA Basic Starter Kit and create the XBLIG Sales Data Analyzer in 2012.
Download here: http://tinyurl.com/aznc2011