At the dock screen, press Left(2), Right(2), L2, R2, R1, L1, Square, Triangle.
Press Up on the D-pad several times.
Kill 100 Aircraft as the Japanese to unlock the 203mm Chain Gun. It has the following stats: Offensive: 400, Weight: 100, Range: 3500, Ammo: 5000, only available for Battleships or Battle Carriers.
Kill 100 Aircraft as the Americans to unlock the 30mm CIWS.
Kill 500 Aircraft as the Japanese to unlock the 356mm Chain Cannon.
Kill 999 Aircraft to unlock the 406mm Chain Gun.
Kill 100 PT Boats to unlock the 46cm 60 Caliber Deck gun, only available for Battleships and Battle Carriers.
Kill 100 Cruisers to unlock the 80cm Guided Torpedo.
Kill 100 Destroyers to unlock the Atomic Engine Alpha.
Kill 500 Destroyers to unlock the Atomic Engine E with the following stats: Output: 22,000, Weight 600.
Kill 100 Battleships to unlock the Charged Particle Gun 3.
Kill 100 Submarines to unlock the Enigmatech Atli, with the following abilities: Top Speed +10%, Rudder Response +1, Control Ability +25%, Endurance +500.
Kill 500 Transports to unlock a Twin Hull Battleship.
Kill 100 Transports to unlock a Twin Hull Cruiser with a 10,000 ton weight limit.
Kill 100 Superships to unlock the Wave Gun. It has the following stats: Offense: 18,000, Range: 20,000, Weight: 4,000, Reload time: 1,000, Ammo: 5.
Kill 999 Transports to unlock the Xbattlecarrier.