You were going to the National Park which you cleaned. You were thrown to a teleporter. You reached Metal World the hardest labyrinth. You have been stuck there for complete 2 days without water and food. The big mushrooms are to give you shelter, become a symbol of starting of a new layer and give you a small fruit having some water.
This is gonna be the last day if you don't rescue and go to the portal. The goal is your portal to Earth. Reach the goal ASAP!