Apocalypse: Rebirth, Start a Dungeon

Front row tips: (farming + system + mecha + no female protagonist) Heavy fog filled the air, and strange purple light waves followed a violent impact, bringing about a strange doomsday. Fast-moving infected people, mutated and evolved beasts, terrifying alien creatures... Human beings are no longer the masters of the earth's surface. Ye Feng, who sold his property to purchase supplies, obtained an underground city that could save human civilization. He collected resources and built facilities. The technology of the underground city was constantly lighting up... At an altitude of 10,000 meters, the behemoth Leviathan is torn apart by the Skyfire Mecha. In the endless deep sea, the battleships of 10,000 meters in the sky declare the sovereignty of mankind. Numerous turrets stand on the dangerous surface. Human beings who have been expelled underground will return to the surface again.