You have fallen in a underworld prison because mole people dont like earth people. They will keep throwing rocks at you, so you have to move fast. Go in the rooms looking for the keys to the prison. D labels are doors press E to open them. Press E next to the chests to search them. L label is the level door that will only open once you get all keys. If time runs out you loose too!
There doesn't seem to be anything here.