When Doomsday Comes, I Can Upgrade My Refuge Infinitely

On January 1, 2022, doomsday came to the earth, and the whole world would be exterminated. Jack was accidentally reborn three months ago. Knowing that the end of the world was coming, he immediately began to build a refuge. He also activated the Doomsday Survival System, which could help him constantly upgrade his refuge. The bulky iron door had been upgraded to a titanium alloy fire-resistant insulated door! The brick concrete walls had been upgraded to special space metal walls! The power system, pipeline system, material storage system, and active defense system had all been upgraded. Jack's refuge was as complete and elaborate as a space station! When the other survivors were still struggling to survive in the ruins of the apocalypse, they suddenly saw a huge refuge.