The struggle for survival has ultimately ended in failure. The surroundings are filled with shadows of death, and the air vibrates only with the foul stench of something burnt and the odor of rotting cells. Over the records of humanity's brilliant civilization, history, and its total downfall, the last withered rose of the artificial garden snaps weakly and falls to the ground. Watching the petals, which must have been red and beautiful once, return to the soil in black decay, you breathe heavily behind your gas mask. It seems you are the only living thing left moving in this world. Just as you are about to take a step, a mysterious sound begins to drift toward you from deep within the thick fog.