Microsoft XNA (a recursive acronym for XNA's not acronymed) is a freeware set of tools with a managed runtime environment provided by Microsoft that facilitates video game development and management. XNA is based on the .NET Framework, with versions that run on Windows NT, Windows Phone and the Xbox 360. XNA content is built with the XNA Game Studio, and played using the XNA Framework (for Windows games), or published as native executables (for Xbox 360, Windows Phone and Zune). 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 that run on a variety of Microsoft platforms. XNA is the basic platform for Xbox Live Indie Games. The XNA toolset was announced 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. XNA Game Studio 2.0 was released in December 2007, followed by XNA Game Studio 3.0 on October 30, 2008. XNA Game Studio 4.0 was released on September 16, 2010 along with the Windows Phone Development Tools. According to an email sent on 31 January 2013, XNA is no longer actively being developed, and it is not supported under the new "Metro interface" layers of Windows 8 nor on the Windows RT platform. An open source cross platform version of the Microsoft XNA 4 Application programming interface called MonoGame is actively being developed.