Polderland - Concept-Art

This is my personal project, the concept of which conveys the story of a post-apocalyptic world, where humanity is trying to adapt to a new reality in a flooded world, while at the bottom of the ocean a new life is born, claiming primacy over humanity in this world.
The main point in this concept is that humanity is trying to find a new safe place to live and called it Polderland - part of an unsinkable place representing something like Fortified City.
I assume that the genre of this game might be a co-op survival adventure game where gamers have to fight off amphibian enemies and find the Polderland.