Get Past the bats/moths in Hard mode in Shopping Mall
During Hard mode, you will encounter some bats/moths that block your path. Go back out to the hallway and look at the fan. There is a switch which you can use. Use it to turn off the fan, then go back into the hallway with the bats/moths. Use the pail to mix the detergent and bleach found in other areas of the mall, then turn the fans back on to eliminate the poisonous gas that is created by mixing the two.