Keys are a ladder. A White Key opens an intermediate door, often the door that holds a Red Key. A Red Key opens weapon rooms and the doors that hold a Green Key. A Green Key opens Tommy Gun and Giant Potion vaults.
If you die while holding a key, it drops on that spot. A key ring from Halls, Sawblades, or Spleef keeps keys when you die. One Chained Office route uses that ring on purpose: grab the green key and drop into the void so the ring returns it with you.
White Key rooms
Pick these up with no trade.
- Ball Ramp: on the central pipe. Jump from the rolling stones. Smilers can use a Jump Potion or shove a boulder.
- Cornlab: five spots, including beside the corn NPC, on ceiling lights, and toward the exit. Corn entities hit people in the stalks.
- Dead Forest: on the observation camera.
- Desolate Shelter: end of the spiral in the second sector.
- Double Gate: hallway floor or the table, near infection.
- Exhaust Room: floor corners under the fan. Use the side ladders.
- Halls: three second-floor spots, one of them near the key ring.
- Isolated Mineshaft Industry: lower obstacle course, alongside a sword.
- Lockers: sometimes inside a rusty locker.
- Steel Bridges: lower beams under the crossing.
- Towers: top of the four towers, by ladder.
- Vents: right-hand laser path near the ladder.
- Warhead: lower ruins when the hatch opens.
What the higher keys buy
Red doors in Lockers and the Sewers are the usual trade from red to green. Aquarium's green key is not a trade: break the tank by dropping the beam, kill the shark, and take the key from the opened side room. Bacon Site 9 puts a green key in the Giant Laboratory after you roll a bomb into the scientist cell. The yellow-coated researcher keeps a revolver. Warhead's collapse also drops all three colors on the lower floor.
Green doors are the rooms people camp. Open one only when you can leave with the Tommy Gun or the Giant Potion. In Headcam, taking the potion removes the guns, so decide which item the round needs.