Valve had promised the announcement of a new project today, so it proved. The U.S. company has just announced the development of Defense of the Ancients 2, also called as Dota 2. A sequel that will go to PC and Mac, and will be launched in 2011.This sequel will continue the premises of its predecessor, with a mix of strategy and RPG game online action, keeping more than 100 original heroes, items, skills and improvements such as the use of Source engine.The game is being created by Valve in collaboration with Icefrog. Valve founder Gabe Newell said "IceFrog was one of the smartest people we've ever met about doing that, and he was doing it with both hands tied behind his back, so to speak."Along with the announcement, Valve has released a series of artworks that you can see below.