信長の野望シリーズ
The company initially focused on personal computer sales and made-to-order business software. In 1983 it released "Nobunaga's Ambition" (信長の野望 "Nobunaga no Yabō"), a historical strategy game set during the Sengoku period of Japanese history. The game went on to receive numerous awards, and Koei produced several more such games set against the backdrop of world history, including "Romance of the Three Kingdoms", set during the Three Kingdoms period of Chinese history, and "Uncharted Waters" (大航海時代 "Dai Kōkai Jidai"; lit. "Great Navigation Era"), set in Portugal during the Age of Exploration.