Apocalyptic Disaster: I Have a Mobile Fortress with Unlimited Upgrades

"Global Catastrophe + Rebirth + Stocking Up Materials + Upgrading Fortress + Farming + Late-stage Island" Global catastrophes, blizzards, earthquakes, tsunamis, volcanic eruptions, large amounts of radiation radiated around the world, causing biological mutation, and 90% of the world's people perished! Ning Zhi was reborn and returned to the university dormitory. In his previous life, he had ignored the spam messages on his mobile phone, but he did not expect that this would be the key to building a fortress. "Fortress name: Self-built house?" "Safety level: Level 0?" "Defense measures: None?" Ning Zhi returned home two weeks before the disaster and started his own crazy construction. No supplies? Take all the super malls away! No energy? Let the first-level gas stations disappear into thin air! The water covers the golden mountains, the rich get on the boat, and the poor climb to higher places. "Captain, look! There is a house floating on the water a thousand nautical miles away!"