Age of Empires II is a real-time strategy game that focuses on building towns, gathering resources, and creating armies to defeat opponents. Players conquer rival towns and empires as they advance one of 13 civilizations through four "Ages": the Dark Age, the Feudal Age, the Castle Age (being the High Middle Ages), and the Imperial Age, reminiscent of the Renaissance—a 1000-year timeframe. Advancing to a new Age unlocks new units, structures, and technologies, but players must first build certain buildings from their current age and then pay a sum of resources (typically food and gold).