The End of the World: Start by Picking up Wood to Upgrade Your Fortress

On the 107th day of the virus outbreak, Chen Lan was trapped in the basement with only three days of food left. When I pried open the neighbor's door, I didn't find the can, but I found a blood-stained wooden board. The fortress upgrade system is activated instantly! Collect wood to build walls, hunt zombies to accumulate crystal cores, and go from a 1 square meter shelter to a three-story steel fortress. Three days later a wave of corpses besieged the city, and he raised the fortress from the ruins. The survivor looked down and said coldly: "Want to survive? Give me the crystal core in exchange!"