The crucial areas, or rather points, of the map are the ports, and the units at the player's disposal are his warships. The winner is the player that controls the largest port capacity at the end of the game, i.e. after a certain number of game turns or a pre-determined time. Players gain income from their ports. They spend their income for increasing port capacity, fortifying ports, building shipyards, and building ships. Ships have no inherent value towards the objective of the game, but they are necessary to protect the bases.
New technology makes older ships obsolete, forcing players to constantly upgrade their fleets.
When opposing ships or fleets meet, or ships enter a fortified port, game play switches to short interludes of tactical battle. 2nd edition June 1999. Some game aid sheets I made for my own use are available for download . In most cases he has some freedom of choice what to buy with the available economy points. Scenario rules may also set the level of technology available and may limit the playable area.