To Survive a Natural Disaster, I Work as a Cleaner in the Dungeon

At first, people thought it was just an ordinary rainstorm... The whole world became a vast ocean, heavy rains fell for half a month, and countless people died in the floods. Unexpectedly, a game system appeared. [It is detected that intelligent life on Blue Star is about to become extinct, and rescue procedures are launched. Chen Sanxing did not expect that the rescue mentioned by the mysterious voice turned out to be to extract dungeon cards, allowing them to choose to enter the dungeon to complete the task, and get supplies if they survived. Food, weapons, medicine, daily necessities... As long as you can complete the mission and survive, you can get what you want. Chen Sanxing did not expect that the star stone he picked up would become his plug-in system 258, allowing him to survive the natural disaster. However, there is something wrong with this 258 system. Also, why do all the copies he experienced have problems?