How to play domino puzzle online

Cover the whole number grid with two-square dominoes. Every domino joins two horizontally or vertically adjacent squares. Each unordered number pair must appear exactly once.

What “unordered” means

A domino containing 0 and 1 is the same pair whichever way it faces. You may not use both 0–1 and 1–0 as separate dominoes.

The small set

The first four boards use numbers 0, 1 and 2. You need six dominoes: 0–0, 0–1, 0–2, 1–1, 1–2 and 2–2. The remaining four use 0 through 3 and need all ten unordered pairs. The pair list marks those already placed.

Place and remove

Select an unpaired square and its neighbour. Diagonal pairing and wrapping from one row’s last square to the next row’s first are not allowed. Already paired squares cannot overlap a new domino. Select either square of an existing domino to remove it.

Hints and keyboard

Each puzzle has one solution. Hint removes a wrong pair before placing a correct pair. Use Undo to take back a hint.

Tab to a square and press Enter or Space. Arrow keys move focus by row and column. Every square must be covered and every required pair used once to finish.

Your progress

Each puzzle keeps its own moves in this browser. Choose another puzzle to revisit it. Undo also takes back a hint or restart. If saving fails, the notice gives the reason and a recovery action. Damaged saved data is kept until you explicitly replace it.