AquaNox

AquaNox is an submarine action adventure game set many years after a global nuclear war has forced all the survivors to settle underwater. During a period of political unrest, a huge landslide opens a series of underwater caverns and frees some ancient gods that had been imprisoned for aeons. You play as the character Emerald "Dead Eye" Flint, a submarine pilot who battles in his quest to save human civilization. Even five years after the fierce fight against a robotic species called Bionts the world of "Aqua" still can't be at peace. On the contrary. Without suspecting anything it is being put to its hardest test and you are right in the middle of it. Flint participates in glorious battles and action-crammed underwater dogfights.