Global Cataclysm: Unlimited Upgrades to the Vault

The sun flares erupt, huge meteorites descend, the cataclysm is imminent, and the horrific scene of the Ice Age and the extinction of dinosaurs is about to reappear.

Wu Di crossed into this world and immediately faced the end of the world!

Fortunately, he got the brain of the machine and opened his own sanctuary system, which can be upgraded infinitely!

Iron door→Mezzanine door→Alloy door→Laser channel……

Crossbow shooting port → small-caliber machine gun → large-caliber machine gun → thunderstorm machine gun → machine light cannon…

Radiation suit → exoskeleton armor → mechanical armor → small mecha → giant mecha……

Crossbow making bench → gun workbench → gun making room……

……

(PS: The shelter has infinite upgrades, the background of the catastrophe doomsday, the new book is open, please collect it!)