Global Catastrophe, Infinite Upgrade of Shelters

The shelter system is awakening at the beginning, there are still eight months until the global catastrophe! Earthquakes, tsunamis, volcanic eruptions, meteorite falls, ice ages... Facing the coming catastrophe, Chen Yi began to build his own 'shelter'. Iron door→Alloy door→Double door→Laser channel... Cold weapon manufacturing bench → Gun manufacturing bench → Electromagnetic gun manufacturing bench... Machine gun turret→Multi-barreled machine gun turret→Electromagnetic gun ps: This book is a post-apocalyptic story, and it's quite dark. This novel and its characters are purely fictitious. Any similarity is purely coincidental and should not be imitated.