I just uploaded (on GitHub) the source code for the Super Smash Bros. Brawl 3D Model Viewer XNA 4.0 Game Studio that I worked on with a friend a few years ago. You can find the source code under my GitHub account (huhx015). The program requires 3D models and audio assets to compile, but I have omitted the content files, for cooyright reasons.
For those that are unfamiliar with the XNA framework, it was a library that Microsoft had made available to indie game developers to promote the development of indie games on the Xbox360 and Windows Phone platforms. XNA was a great way to get into developing games relatively quickly, as the framework’s libraries made building a 2D/3D game far more simpler.
However, with the switch to Windows 8 & Windows Phone 8 platforms and focus on the unified RT framework, Microsoft decided to kill off XNA.