The PC Version was released on October 18, 2005 in North America and November 4, 2005 in Europe, while the Mac version was released on November 21, 2006 in North America and September 29, 2006 in Europe. It is the third game of the Age of Empires series and the sequel to Age of Empires II: The Age of Kings. The game portrays the European colonization of the Americas, between approximately 1492 and 1850 AD (expanded in Age of Empires III: The WarChiefs to 1876). There are eight European civilizations to play within the game.

Age of Empires III has made several innovations in the series, in particular with the addition of the "Home City", which combines real-time strategy and role-playing game features. Two expansion packs have been released: the first, Age of Empires III: The WarChiefs, was released on October 17, 2006, and introduced three Native American civilizations; the second, Age of Empires III: The Asian Dynasties, was released on October 23, 2007, and included three Asian civilizations.

Age of Empires III has sold over 2 million copies as of May 2008. As well as achieving favorable reviews, it has received awards, including GameSpy's "Best RTS game of 2005", and was one of the best-selling games of 2005.^[2] In 2007, Age of Empires III was the seventh best-selling computer game, with over 313,000 copies sold that year.^[3]

An N-Gage version of the game developed by Glu Mobile was released on April 28, 2009