When a massive, mysterious structure suddenly rises from the ground, the government sends a team to investigate. You have been selected to join an elite group of underground explorers know as "Undernauts" employed by the Cassandra Company. Unfortunately, you are not the only one searching the caverns. Terrifying monsters lurk in the shadows. Others hunt for resources. Large numbers of people are missing. Dangerous criminals with mysterious powers are out to thwart your eorts and eliminate your team. The ultimate test for survival is found in the labyrinth. Can you be victorious and rise above the shadows? Recover the "darkness" hidden deep within the labyrinth. Use the "Switch Boost" system to defeat hordes of monsters. Create magical doors, ladders, and bridges to escape the labyrinth.