Dota 2 is a free-to-play multiplayer online battle arena (MOBA) video game developed and published by Valve Corporation. The game is the stand-alone sequel to Defense of the Ancients (DotA), which was a community-created mod for Blizzard Entertainment’s Warcraft III: Reign of Chaos and its expansion pack, The Frozen Throne. 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 powerful character, known as a “hero”, who all have unique abilities and differing styles of play. During a match, players collect experience points and items for their heroes to successfully battle the opposing team’s heroes, who attempt to do the same to them. A team wins by being the first to destroy a large structure located in the opposing team’s base, called the “Ancient”.
Development of Dota 2 began in 2009 when IceFrog, the pseudonymous lead designer of the original Defense of the Ancients mod, was hired by Valve to create a modernized sequel. Dota 2 was officially released for Microsoft Windows, OS X, and Linux-based personal computers via the digital distribution platform Steam in July 2013, following a Windows-only public beta phase that began two years prior. Despite some criticism going towards its steep learning curve and complexity, the game was praised for its rewarding gameplay, production quality, and faithfulness to its predecessor, with multiple gaming publications later considering it to be one of the greatest video games of all time. The game initially used the original Source game engine until it was ported to Source 2 in 2015, making it the first game to use it. Since its release, Dota 2 has been one of the most played games on Steam, with over a million concurrent players at its peak. The popularity of the game has led to official merchandise for it being produced, including apparel, accessories, and toys, as well as promotional tie-ins to other games and media. The game also allows for the community to create custom game modes, maps, and hero cosmetics, which are uploaded to the Steam Workshop and curated by Valve.