The Shutter is a game mechanic that covers part of the game board, hiding a specific area and blocking your access to it.
To unlock the Shutter, you must meet one of these conditions:
Remove a certain number of shapes of any color.
Remove a certain number of shapes of a specific color.
Note: "Removing shapes" means you must fill and remove the boxes that those pieces are placed in.
Until you meet these conditions, the area behind the Shutter is completely inaccessible. You will not be able to see or interact with any of the objects hidden there.
Once you meet the requirements, the Shutter will open, and you can play in the previously hidden part of the board!