The Aquatic Adventure of the Last Human

From kickstarter: "The Aquatic Adventure of the Last Human is a metroid-vania styled action/adventure game where you play as the navigator of Argo 9, a spaceship/submarine hybrid, thrust back to Earth in a time after humans have gone extinct. Whereupon one will have to explore to uncover the reasons for humanity's downfall meanwhile encountering monstrous sea creatures. The focus of this game lies in exploration, story and boss battles. It is up to the player to determine if the ruins of our species is a travesty or an inevitable conclusion."

Story

From official web: "In the far future humanity is no more. The earth has been flooded for centuries and without humans the wild-life is thriving. Take control of the long lost space ship-submarine hybrid Argo 9 on a spectacular adventure to a not so familliar homeworld."