Caleb, a legendary soldier, activates the Doomsday Bunker System as the apocalypse begins. With a welder and a modded harvester, he builds a mechanical farm on Sunset Hills. While humanity struggles against zombies and famine, he feasts in a bulletproof greenhouse and grows antiviral wheat. Stockpiling grain, building walls, and recruiting elite survivors, he transforms the farm into a steel fortress with heavy guns and Titan Mechas.