[publisher's description] On Seapower (OS) is a card game of naval innovation in the period before the Great War (roughly 1875-1920). Players take the role of Great Britain, France, the United States, or Germany. Each nation must plan and execute the development of a fleet during peacetime, and then test its capabilities in a series of wartime Missions. In the game, cards represent Ships, Technologies, Doctrines, Innovators, and Random Events. As the international Tension Level rises toward an inevitable War, players must make tradeoffs between building new ships using the best current technology, or investing in the development of more advanced weapons and platforms, to be built later.