Dota 2 is a multiplayer online battle arena video game and the stand-alone sequel to the Defense of the Ancients (DotA) mod. Developed by Valve Corporation, the game was released on July 9, 2013 for Microsoft Windows, utilizing a free-to-play business model. OS X and Linux versions of Dota 2 were released on July 18, 2013. Dota 2 is exclusively available through Valve's content delivery platform, Steam.
The game consists of session-based online multiplayer matches, in which two teams of five players attempt to destroy their opponents' fortified strongholds. Each player controls a "hero" character and, over the course of an individual game, focuses on improving their hero's abilities, acquiring items, and fighting against the other team.
Development of Dota 2 began in 2009, with the hiring of DotA's lead developer known as "IceFrog" to serve as the lead designer for a sequel. To design the graphics, Valve used an upgraded Source engine to accommodate features necessary for the game. Dota 2 was acclaimed by video game critics as being one of the most successfully delivered multiplayer online battle arena games, with praise for the gameplay experience, which was considered engaging and rewarding at the cost of a steep learning curve.