Play is selling "Age Of Empires III: Gold Edition" for the PC for £17.99 (inc Del.)
You can get cashback from the usual sites (e.g. 4% Quidco, making it just £17.27)
Next best price is £24.99 from Game
The Gold Edition includes "Age of Empires III" and "The War Chiefs" Expansion Pack.
Age of Empires III
In this highly anticipated next installment in the Age of Empires franchise from Ensemble Studios, Age of Empires III places players in the time period of roughly 1500-1850, picking up where Age of Empires II: The Age of Kings left off. As players work to establish their empire, they will take on the role of a European power struggling to explore, colonize and conquer North and South America. Age of Empires III introduces exciting new gameplay elements, including the all-new Home City and an incredible combat system. Players will find new civilizations to discover, random maps to conquer and a single-player campaign unlike any other. Players also will find stunning graphics as a result of a revolutionary graphics engine that pushes the limits of PC graphics technology in an entirely new way.
The War Chiefs Expansion Pack
Age of Empires III: The War Chiefs is the new expansion pack for the best-selling real-time strategy (RTS) title of 2005: Age of Empires III. Age of Empires III: The War Chiefs will engage gamers of all ages and types in epic warfare in the Americas, where they will lead proud, playable native civilizations to expand their empire and fight for control of the Americas.