Key items are essential for progression, unlocking new areas, and solving puzzles. They range from simple keys to complex mechanical parts. Always examine key items in your inventory for clues. Once a key item has served its purpose (e.g., a key has opened a door), it will often be marked as 'DISCARD' in your inventory, allowing you to free up space. Examples include the Locker Key, Battery, Fuse, Power Cable, Oil Additive, and various Gears. Pay close attention to file descriptions, as they often hint at the location or use of these crucial items.
