Each board is a 36 by 36 square tiled with smaller squares. The goal is to figure out which hidden squares belong in the dark empty spaces.

• Use the board buttons, board number field, or Go button to choose a puzzle.
• Use Random Puzzle to choose a random board with a generated set of missing squares.
• Left-click a visible square to hide it.
• When squares are hidden, move over the board to preview a tentative square.
• Use the mouse wheel over the board to change the preview size from 1 to 8.
• Left-click an empty space to place the matching hidden square there.
• Use Get Puzzle URL to copy a shareable link for the current board and hidden squares.