Gunship Battle: Crypto Conflict

In the near future, global warming has accelerated past all prjections. With seas on the rise and mass migration across every ocean and continent, conflict break out across the globe and threaten to become an all-annihilating World War III. Armada has released a propaganda video claiming it soon will acquire a nuclear weapons on its own. Armada was getting ready to declare a nuclear war, to eradicate peace of the world. But, the old world order died in their place, along with countries, military, and your own navy. Only a single battleship, crew, and a deserted island were left behind you.