 Those 'credits' can then be used to upgrade the various vessels owned by Emerald 'Deadeye' Flint with a huge array of offensive and defensive upgrades, such as additional, and/or more powerful primary weapons, torpedoes and torpedo storage and turret command software, generators, hull plating, Buzzers (technically underwater flares to break a torpedo's lock on the player's ship), noise reduction technology, a booster, and a fixer.The control of the game is designed for the use of a joystick.The player is confronted with maneuvering through narrow canyons, deep sea currents and enemy fire.