Team Fortress 2 is a team-based multiplayer first-person shooter developed by Valve Software as part of the game bundle The Orange Box. It was first released for Microsoft Windows and Xbox 360 on October 10, 2007. Following suit, it was released as a standalone title on April 9, 2008, and on June 10, 2010, Team Fortress 2 was released for Mac OS X. The PC and OS X versions of Team Fortress 2 adopted a "Free to Play" model on June 23, 2011, with all revenue being generated from microtransactions in the In-game Store. After several months of closed beta, Team Fortress 2 was finally released for Linux operating systems on February 14, 2013.