Portal is a first-person puzzle-platform video game developed by Valve Corporation. The game was released in a bundle package called The Orange Box for Microsoft Windows and Xbox 360 on October 9, 2007, and for the PlayStation 3 on December 11, 2007. The Windows version of the game is available for download separately through Valve's content delivery system Steam and was released as a standalone retail product on April 9, 2008. More: en.wikipedia.org.