Dota 2 is a 2013 multiplayer online battle arena (MOBA) video game by Valve. The game is a sequel to Defense of the Ancients (DotA), a community-created mod for Blizzard Entertainment's Warcraft III: Reign of Chaos. Dota 2 is played in matches between two teams of five players, with each team occupying and defending their own separate base on the map. Each of the ten players independently controls a character known as a hero that has unique abilities and differing styles of play. During a match, players collect experience points (XP) and items for their heroes to defeat the opposing team's heroes in player versus player (PvP) combat. A team wins by being the first to destroy the other team's Ancient, a large durable structure located in the center of each base.
Development of Dota 2 began in 2009 when IceFrog, lead designer of Defense of the Ancients, was hired by Valve to design a standalone remake in the Source game engine. It was released for Windows, OS X, and Linux via the digital distribution platform Steam in July 2013, following a Windows-only open beta phase that began two years prior. Dota 2 is fully free-to-play with no heroes or any other gameplay element needing to be bought or otherwise unlocked. Valve supports the game as a service, selling loot boxes and a battle pass subscription system called Dota Plus that offer non-gameplay altering virtual goods in return, such as hero cosmetics and audio replacement packs. The game was ported to the Source 2 engine in 2015, making it the first game to use it.