Rise of Nations is a real-time strategy computer game, developed by Big Huge Games and published by Microsoft on May 20, 2003. The development of the game was led by veteran Brian Reynolds, of Civilization II and Sid Meier's Alpha Centauri. Concepts taken from turn-based strategy games have been added into the game—including territories and attrition warfare. Rise of Nations features 18 civilizations, playable through 8 ages of world history.