Team Fortress 2 is a team-based first-person shooter multiplayer video game developed by Valve Corporation. It is a sequel to the original mod Team Fortress and its GoldSrc engine remake. It was first released as part of the video game compilation The Orange Box on October 10, 2007 for Windows and the Xbox 360. A PlayStation 3 version then followed on November 22, 2007. The game was later released as a standalone package for Windows on April 8, 2008, for OS X two years later, and for Linux on February 14, 2013. Team Fortress 2 is distributed online through the download retailer Steam, while retail distribution was handled by Electronic Arts. On June 23, 2011, the game became a free-to-play title, supported by microtransactions for unique in-game equipment through Steam. The development of Team Fortress 2 is led by John Cook and Robin Walker, who originally created the Team Fortress modification for Quake in 1996.