Nobunaga's Ambition: Taishi takes place during the Japanese Warring States period. As the title suggests, the player is tasked with achieving Oda Nobunaga's ultimate goal: the conquest and unification of Japan. Selecting Nobunaga is optional, however, as the player is can choose from a variety of other regional daimyo of the time. Available daimyo changes based on historical scenario the players selects to play.
The game plays in a similar manner as the Romance of the Three Kingdoms series but has a few distinguishing differences. Unlike the former, the imperial court plays a greater role in deciding the damiyos' fate. If the court favors them, players have the option to name someone an enemy of the state, call a ceasefire, or promote their rank.