On February 14, 2013, Valve released a Linux version of Steam, a popular game distribution platform on PC. Many Steam games were ported to Linux. On December 13, 2013, Valve released SteamOS, a gaming-oriented OS based on Debian, for beta testing, and has plans to ship Steam Machines as a gaming and entertainment platform. Valve has also developed VOGL, an OpenGL debugger intended to aid video game development, as well as porting its Source game engine to desktop Linux. As a result of Valve's effort, several prominent games such as "DotA 2", "Team Fortress 2", "Portal", "Portal 2" and "Left 4 Dead 2" are now natively available on desktop Linux.