Dota 2 is a video game. It is a sequel to Defense of the Ancients. Dota was originally a player-made map in Warcraft: Frozen Throne that was very successful. When Warcraft: Frozen Throne game got old, it was hard to make the map. As a result, Valve Corporation, with the help of the original maker (known only as Icefrog) started to develop Dota 2.