The scenario was developed with the "World Editor" of Warcraft III: Reign of Chaos, and was updated upon the release of the Warcraft III: The Frozen Throne. There have been many variations of the original concept; currently, the most popular is DotA Allstars, which has been maintained by several authors during development.
Since its release, Allstars has become a feature at several worldwide tournaments, including Blizzard Entertainment's BlizzCon and the Asian World Cyber Games, as well as the Cyberathlete Amateur and CyberEvolution leagues; Gamasutra declared that DotA was perhaps the most popular "free, non-supported game mod in the world." The map has gone on to influence other maps and games, including the strategy game League of Legends and Heroes of Newerth.
Defense of the Ancients pits two teams of players against each other: the Sentinel and the Scourge. Players on the Sentinel team are based at the southwest corner of the map, and those on the Scourge team are based at the northeast corner. 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", a building that must be destroyed to win the game
Each human player controls one Hero, a powerful unit with unique abilities. In Allstars, players on each side choose one of over one hundred different heroes, each with different abilities and tactical advantages over other heroes. The scenario is highly team-oriented; it is difficult for one player to carry the team to victory alone. Nevertheless, some heroes, given enough time, can change the outcome single-handedly, while countering the opposing team's heroes. Defense of the Ancients allows up to ten players in a five versus five format and an additional two slots for referees or observers, often with an equal number of players on each side.
Because the gameplay revolves around strengthening individual heroes, it does not require one to focus on resource management and base-building, as in most traditional real-time strategy games. Killing computer-controlled or neutral units earns the player experience points; when enough experience is accumulated, the player gains a level. Leveling up improves the hero's toughness and the damage it can inflict, and allows players to upgrade their spells or skills. In addition to accumulating experience, players also manage a single resource: gold. The typical resource gathering of Warcraft III is replaced by a combat-oriented money system; in addition to a small periodic income, heroes earn gold by killing hostile units, base structures, and enemy heroes. Using gold, players buy items to strengthen their hero and gain abilities. Certain items can be combined with recipes to create more powerful items. Buying items that suit one's hero is an important tactical element of the scenario.
Allstars offers a variety of game modes, selected by the game host at the beginning of the match. The game modes dictate the difficulty of the scenario, as well as whether people can choose their hero or are assigned one randomly. Many game modes can be combined (for example, an easy difficulty level and a random hero pick), allowing more flexible options.
The first version of Defense of the Ancients was released in 2003 by a mapmaker under the alias Eul, who based the map on a previous StarCraft scenario known as "Aeon of Strife", After the release of Warcraft's expansion The Frozen Throne, which added new features to the World Editor, Eul did not update the scenario. Other mapmakers produced spinoffs that added new heroes, items, and features.
Among the DotA variants created in the wake of Eul's map included Allstars, developed by modder Steve Feak (under the alias Guinsoo); this version would become the most popular version of the map. Feak said when he began developing Allstars he had no idea how popular the game would eventually become; the emerging success of the gametype inspired him to design a new title around what he considered an emerging game genre. Feak added a recipe system for items so that player's equipment would scale as they grew more powerful, as well as a powerful boss character called Roshan (named after his bowling ball) who required an entire team to defeat. Steve "Pendragon" Mescon created a community site, dota-allstars.com, in 2004 to replace the battle.net channel Feak created to provide a place for DotA players to congregate.
Towards the end of his association with the map, Feak primarily worked on optimizing the map before handing over control to another developer after version 6.01. The new author, IceFrog, added new features, heroes, and fixes. Each release is accompanied with a changelog. IceFrog is notoriously reclusive, refusing to give interviews; the only evidence of IceFrog's authorship is the map maker's email account on the official website and the name branded on the game's loading screen.
Defense of the Ancients has strong community support, now maintained via official forums. Users can post ideas for new heroes or items, some of which are added to the map. Players have contributed icons and hero descriptions and created the artwork displayed while the map loads, and suggestions for changes to existing heroes or items are taken seriously; IceFrog once changed a new hero less than two weeks after the new version of the map was released. Versions of the scenario where enemy heroes are controlled by artificial intelligences have also been released.
Because Warcraft III custom games have none of the features designed to improve game quality (matchmaking players based on connection speed, etc.), various programs are used to maintain Defense of the Ancients. External tools ping player's locations, and games can be named to exclude geographic regions.REFG Clans and committees such as Team DotA Allstars (TDA) maintain their own official list of rules and regulations, and players can be kicked from matches by being placed on "banlists".
Defense Of the Ancients 2 is currently being developed as a successor to Defense of the Ancients by Valve Corporation and IceFrog. DotA 2 was officially announced on the 13th of October 2010 and a public beta is scheduled for Fall 2011. The final release is expected to be released sometime in 2012. DotA 2 will be released through both download and retail and will operate on the Steam platform.