Global Cataclysm: I’m the Only One with a Shelter

In 2111, disaster strikes! Countless collapses appear all over the world! Terrifying alien creatures pour out of bottomless pits! Meteorite impacts, extreme temperature swings, wave after wave of monster hordes! Lin Cheng transmigrated here a year ago and built a shelter in advance. Three days before the Great Reckoning began, he awakened a System. [Ding! Shelter level increased! System reward: Superconducting Electromagnetic Cannon!] [Ding! A large increase in the shelter's survival supplies has been detected. System reward: Spatial Teleportation Gate!] While people are fighting over a single loaf of bread, Lin Cheng is already mowing down nearby alien creatures with a Gatling gun and drawing up plans for an underground city...