Yes, I recommend " Doomsday Sharpshooter ", a sci-fi-doomsday crisis novel. The male protagonist, Deng Yun, was bound to the gunner system before the doomsday. As long as he killed zombies, he could gain experience. However, he only had a slingshot at the beginning, so he had to constantly upgrade himself to obtain better firearms and weapons to survive. I hope you like my recommendation.😗