Defense of the Ancients (DotA) is a multiplayer online battle arena (MOBA) mod for the video game Warcraft III: Reign of Chaos (2002) and its expansion, The Frozen Throne. The objective of the game is for each team to destroy their opponents' Ancient, a heavily guarded structure at the opposing corner of the map. Players use powerful units known as heroes, and are assisted by allied teammates and AI-controlled fighters. As in role-playing games, players level up their heroes and use gold to buy equipment during the game. DotA has its roots in the "Aeon of Strife" custom map for StarCraft. The scenario was developed with the World Editor of Reign of Chaos, and was updated upon the release of its expansion, The Frozen Throne. There have been many variations of the original concept, the most popular being DotA Allstars, eventually simplified to DotA. The mod has been maintained by several authors during development, with the pseudonymous designer known as IceFrog maintaining the game since the mid-2000s. DotA became a feature at several worldwide tournaments, including Blizzard Entertainment's BlizzCon and the Asian World Cyber Games. Critical reception to DotA was positive, and it has been called one of the most popular mods of any game. DotA is largely attributed as being the most significant inspiration for the MOBA genre. American video game developer Valve acquired the intellectual property rights to DotA in 2009 to develop a franchise, beginning with Dota 2 in 2013. Gameplay Defense of the Ancients pits two teams of players against each other. Players on the "Sentinel" team are based at the southwest corner of the map, and those on the "Scourge" team are based in the northeast. Each base is defended by towers and waves of units which guard the main paths leading to their base. In the center of each base is the "Ancient", the building that must be destroyed to win the game. Each player controls one hero, a powerful unit with unique abilities. In DotA, players on each side can choose one of more than a hundred heroes, each with different abilities and tactical advantages. The scenario is highly team-oriented; it is difficult for one player to carry the team to victory alone. DotA allows up to ten players in a five-versus-five format. Because the gameplay revolves around strengthening individual heroes, it does not require focus on resource management and base-building, unlike most