Rise of Nations is a real-time strategy computer game, developed by Big Huge Games and published by Microsoft Game Studios on May 20, 2003. The development of the game was led by veteran game designer Brian Reynolds, of Civilization II and Sid Meier's Alpha Centauri. The game has taken several concepts from turn-based strategy games such as territories and attrition warfare. Rise of Nations features 18 civilizations, playable through 8 ages of world history. It is consistently ranked and considered to be one of the greatest real-time strategy games of all time.