Nobunaga's Ambition is a strategy game made by
Koei, the first installment being released in 1983. The game puts you in the role of a
daimyō in
Sengoku-era Japan, your goal being to unify the country and earn (or with one clan, keep) the title of
Shōgun. As long as this series remains largely unchronicled in the West, the
article
on
Wikipedia has a brief history of the series you might find relevant. 13 main-series games have been released in Japan, scattered across
an army of platforms.
As of December 17, 2011, a crossover game titled
Pokémon Conquest, featuring elements from
Nobunaga's Ambition and
Pokémon, has been confirmed. It was released by Nintendo and Tecmo Koei on March 17th, 2012 in Japan.
Fans went wild, especially from the
Pokémon side of things possibly due to the
Darker and Edgier crossover aspects.
This game series provides examples of: