Dota 2 is a 2013 multiplayer online battle arena video game and the stand-alone sequel to the Defense of the Ancients (DotA) mod. Developed by Valve Corporation, Dota 2 was officially released on July 9, 2013 as a free-to-play title for Microsoft Windows, concluding a beta testing phase that began in 2011. OS X and Linux versions of Dota 2 were released on July 18, 2013. In most regions, the game is available exclusively through Valve's content-delivery platform, Steam.
Development of Dota 2 began in 2009, when DotA developer IceFrog was hired as lead designer. Dota 2 was praised by video game critics, who lauded it for its rewarding gameplay, enhanced production quality and faithfulness to its predecessor. However, the game was criticised for its steep learning curve and inhospitable community. Dota 2 has become the most actively played game on Steam, with daily peaks at over 800,000 concurrent players.[5]