Surrounded by Zombies, I Build an Invincible Fortress

Zombies overrun the world, turning it into a living hell in an instant. Chen Chong isn't worried: fear comes from not having enough firepower. M4A1 carbines, anti-materiel sniper rifles, RPG launchers, fully armored tanks, autonomous self-propelled artillery, drone bomber squadrons, exoskeleton combat robots, Pacific Rim mecha battlegroups, EVA Unit-01… He hunts zombies, upgrades his equipment, and builds a fortress. At last, one day, an unstoppable steel tide of mechanized troops emerges, and the zombies experience an emotion called fear for the first time… (No female lead + decisive and ruthless + self-interest)