Nobunaga's Ambition: Iron Triangle is another entry in KOEI's long-running series of grand strategy games. As in the previous instalments, the player assumes the role of a Japanese feudal lord during the famous Sengoku period (from the XV to the XVII century).
The main game screen shows an overhead 3D rendered view of the landscape, showing buildings and moving armies belonging to each clan. The player gives orders using a menu with a list of commands, that branch out with several options: City (to construct buildings), Personnel (to employ officers), Military (to move and attack with the army), Strategy, Diplomacy (to negotiate treaties and exchange technology) and others to review the resources. The game is paused while issuing the orders, and they are only executed when in Active mode, where time passes and seasons change.
The different seasons have an impact on certain resources and activities, like harvesting and drafting. The scheduled actions and rank position of the clans can be reviewed at any time, on a separate screen. The game has several scenarios and special modes, with historical notes coming up when the game time synchronizes with some major events in Japan's timeline.