Lost Ark: New worlds

A man lost, silent, and unfazed by death becomes the first to experience an awakening on earth after humanity has fallen. He travels through dungeons and through new worlds to get back. He is one of the only people who had survived the nuclear apocalypse. Due to the nuclear waste, all living things began to mutate. With humanity on It's last leg, the nuclear explosions began to cause the already existing dungeons to crack. With only one awakened left, will earth survive?