Microsoft XNA

Microsoft XNA (a recursive acronym for XNA's not acronymed) is a freeware set of tools with a managed runtime environment that Microsoft developed to facilitate video game development. XNA is based on .NET Framework, with versions that run on Windows and Xbox 360. XNA Game Studio can help develop XNA games. The XNA toolset was announced on March 24, 2004, at the Game Developers Conference in San Jose, California. A first Community Technology Preview of XNA Build was released on March 14, 2006.

In many respects, XNA can be thought of as a .NET analog to Microsoft's better known game development system, DirectX, but it is aimed at developers primarily interested in writing lightweight games. XNA is the basic platform for Xbox Live Indie Games.

As of January of 2013, XNA is no longer being developed, and it is not compatible with Windows Runtime (the API for developing Metro-style apps), which was introduced with Windows 8.