The year is 2045. Humanity has been invaded by an unknown entity and is on the brink of extinction. The world has completely changed due to the invasion of these entities; cities have been destroyed, and the remnants of civilization have disappeared underground. Humans have become a species driven solely by the instinct to survive, living in constant fear. In this chaotic environment, a small number of surviving scientists are searching for a solution. As a last hope to reclaim the planet and save humanity, they build a seven-layer platform. This platform, constructed underground beneath a ruined megacity, is a massive structure that is part laboratory and part battlefield.