The key puzzle in The Spiral is our least favourite part of Maquette, as it throws the established logic of the game out the window by not really allowing you to perceive important information the way the other puzzles do.
The trick to this puzzle is the fact that you need to think of three rooms, not two. That’s going to be a little confusing right now, but by the end of this guide it will all make sense.
Play through the Spiral level until you reach two rooms, one with a large key and one with two smaller keys. You need to make a medium-sized key to progress through a locked door in the smaller room.
There is little inherent logic here unless you manage to spot that the small holes the two smaller keys are in look like the room you just left that had the very large key. This is hard to spot because of how dark it is. Pick up the small key on the left and place it in the hole on the right. Then, walk back into the dark room and pick up what will now be a medium-sized key.
Drop the key into the hole on the right so that is forms a sort of bridge between the wall and the floor, leading to the left side of the hole. Go back into the dark room and walk up the large key to a secret gap above the room, where you will find another key. Use this key to open the wooden door in front of you in the brightly lit room.
And that’s it, the key puzzle has been completed.