The Soviet Union, under severe pressure after destruction of one of their biggest oil refineries, must secure a new source of oil, and to do that, they must disable the West... which means they must invade Europe and fight NATO to a standstill... And the only way NATO can prevent that from happening is to reinforce their forces with convoys from the US and other countries.

You are in command of one of the US attack submarines. You must hold the ocean against the Soviet navy at all costs, or the land battle will go badly. Part submarine simulator, part dynamic campaign, and part WW3 simulation, Red Storm Rising is an amazing look at modern warfare.