Liberate a port.
Liberate 3 ports.
Liberate all ports and defeat the GAA forces for good.
Fully upgrade your shields.
Fully upgrade your ammunition capacity.
Purchase a supershot.
Liberate the Japanese base.
Liberate the American base.
Liberate the Soviet base.
Liberate the British base.
Liberate the Australian base.
Liberate the Canadian base.
Destroy a submarine group without using torpedos or supershots
Defeat a 4-star aircraft carrier without being hit or using supershots.
Defeat a 4-star battleship without using supershots.
Defeat a 4-star cruiser battlegroup without being hit nor using supershots.
Defeat a 3-star enemy without upgrading your submarine or using supershots.
Defeat a 4-star enemy without upgrading your submarine or using supershots.
Defeat a cruiser group with only one supershot.