Mercenaries Collect Coupons to Build a Doomsday Empire

3 Years ago, an accidental space capture. Six months ago, an erroneous experiment led to a global mutation crisis. Within 24 hours, major cities around the world were paralyzed. Within 72 hours, the military intervened but quickly collapsed and communications were lost. For seven days, the government lost contact, and human civilization entered a state of no government. Chen Jiang, a small town delivery boy, almost monopolizes the town's food delivery. In the early days of the apocalypse, he awakened the "mercenary coupon" system. As long as he kills zombies, he can get coupons, which can be exchanged for all the resources he wants in the system supermarket...