Apocalypse Mechanic

The zombie virus spread throughout the world and caused the end of days. Ye Bei was tricked by his classmate and lost his arm to a zombie. He had to hide away like a cockroach for 50 years to survive. During that time, he managed to build a time machine and returned himself to 50 years ago, before the apocalypse, with the chance to relive his life. Having seen how people acted during the crisis, he swore he'll be more devious, more selfish, and more coldhearted than anyone else. The first thing he'll do, he's going to feed that bitch to the zombies! (Source: Bilibili, translated)