Key items are essential for progression, unlocking new areas, and solving puzzles. These include various Keys (Spade Key, Diamond Key, Heart Key, Club Key), Medals (Unicorn, Lion, Eagle), Valve Handles, Electronic Parts, and more. Each key item has a specific purpose and location. Always examine new items in your inventory for clues. Puzzles often involve finding the correct key item for a specific lock or combining items to create a new tool. The game's map will often highlight locked doors, indicating which key is needed. Don't discard key items until you are absolutely certain they have no further use.
