I Fell into the Underground World and Can't Get Out

It feels so familiar, as if I have seen everything here before... Flies as big as a palm, spiders with big heads, and bees half as tall as a man... There seems to be no end here. We can only go down layer by layer until we reach the abyss underground... Oh my god, it's a dragon! That's Medusa? What, there are actually elves... Where am I and how do I get out? Maybe I shouldn't have come to this damn underground world in the first place... The moment the underground god appears, everything will be over...