From HintWiki

Looking for the three pieces of the key

• Where is the first key piece?
• Where is the second key piece?
• Where is the third key piece?

Locations

• Arrival hall
  • Under the manhole
• Arrival center
• Turbine room
• Main hall
• The Room with a picture of the moon
• The Room with sketches
• Elevator maze
• Rotating room
• Past the rotating room
  • Lava thermometer
  • Generator room