Key items are crucial for progression, unlocking new areas, or solving puzzles. These include various Keys (e.g., Bolt Cutters, Lockpick, Subway Office Key), Fuses for power restoration, and specific Chemical Samples for vaccine synthesis. Always examine key items in your inventory for clues or additional information. Puzzles often involve finding the correct item to use on an environmental object or inputting a specific code. The game's map will often highlight areas where key items are needed, guiding your exploration. Don't overlook any interactive objects.
