The astronauts who set out in search of a new habitable planet have just returned from their failed mission. However, the Earth's surface is no longer habitable & they discover that the remaining population now lives underground. The supposed path there is buried & the only alternative is to dig & dig into the underground city. The elevator is the transport to the underground of the planet. Avoid green acidic fluid. Dig & dig. Cannons & various other objects. Puzzles that involve...