You Were Asked to Survive, and You Built a Nuclear Bomb?

Background settings Chen Bai traveled through the parallel world and found that this world had experienced a huge disaster. In 2045 BC, an asteroid hit the earth, causing serious nuclear leakage and pollution, and the population of Blue Star dropped sharply. Technology, resources, weapons... Once we return to before liberation! Alien invasion is coming, and inexplicable power opens up the "Pure Land" world! Then one person from a country goes to the "Pure Land" to look for resources, and the resources can be returned a hundred times! Chen Bai was selected to go to the Pure Land and awaken the "Survival Upgrade System!" While contestants from other countries were struggling to find resources, Chen Bai started his leisurely life of survival. On the first day, Chen Bai knitted a bomber jacket and successfully kept out the cold. The bomber jacket was upgraded to a bulletproof vest 24 hours later! The next day, Chen Bai made a stone ax and successfully chopped it down. The wooden ax was upgraded to an iron ax 24 hours later! On the third day, Chen Bai built a stone furnace and used it successfully. The furnace was upgraded to an iron furnace 24 hours later! … This novel and its characters are purely fictitious. Any similarity is purely coincidental and should not be imitated.