Skip to content
Lizely

Dominosa

Partition six numbered tiles into adjacent dominoes without repeating any unordered number pair.

Privacy: your files never leave your device. All processing happens locally in your browser.

How to use

  1. 1.Move the outlined cursor with the arrow keys and press Space or Enter to select a first tile.
  2. 2.Move to an orthogonally adjacent uncovered tile and press Space or Enter to form a domino.
  3. 3.Cover all six cells with three different unordered number pairs before two mistakes or an unsolvable remainder ends the run.

About Dominosa

Dominosa is a small logical tiling game built from six visible number tiles. Your job is to cover the two-by-three board with three adjacent dominoes. Every tile must belong to exactly one domino, and each unordered number pair may appear only once.

The disclosed board reads 0 0 1 on the first row and 1 2 2 on the second. A clean solution pairs each vertical column: the left column makes 0-1, the middle column makes 0-2, and the right column makes 1-2. These three value pairs are distinct and cover all six cells. Pair order does not matter, so 2-1 is treated as the same value pair as 1-2.

Use the arrow keys to move the outlined cursor. Press Space or Enter to anchor the first tile, move to an orthogonally adjacent tile, then press Space or Enter again. Mouse and touch users can select the same visible cells. Selecting the anchored tile again cancels it. Already covered tiles are disabled and cannot be reused.

Each accepted domino awards 400 points. Three valid dominoes complete the board at exactly 1,200 points. A selection fails if the two cells are not orthogonally adjacent or if their unordered value pair has already been used. Two invalid selections create a terminal failure state. Restart clears every domino, selection, mistake, and point.

Dominosa also detects a genuine logical dead end before the board is full. After every accepted domino, an exhaustive completion search examines the first uncovered tile, tries each uncovered neighbor whose pair value is still unused, and recursively checks the remainder. If no perfect unique-pair tiling remains, the run is marked deadlocked immediately. This prevents a board that looks active but can no longer be solved.

The isolated test verifies the six disclosed values, proves that the empty board has a completion, proves that a tempting horizontal 0-0 opening leaves no valid completion, simulates the full three-column winning tiling, checks the 1,200-point result, triggers two invalid nonadjacent choices, confirms terminal freezing, and separately verifies cursor movement. The solver operates on the same state used by the interface rather than a simplified test-only copy.

The board uses semantic buttons and CSS grid. It relies only on the site's surface, foreground, line, accent, and danger tokens. There is no canvas, image, drag requirement, random generator, timer, audio, upload, account, hardware permission, download, or network request. The complete game is available from the keyboard, including selection, cancellation, Restart, and the shared Boss Key.

A useful solving habit is to list the value pairs already used, then inspect constrained edge cells before committing a domino. On this small teaching board, vertical pairs expose the core rule clearly. Larger Dominosa puzzles use the same reasoning: coverage alone is insufficient when a duplicated pair would violate uniqueness.

Double-press Escape to replace the game with the spreadsheet-style Boss Key view, then repeat it to restore the unchanged board. Best score stays in local browser storage. Continue with Hashi Bridges, Numberlink Puzzle, Hitori Puzzle, or Number Match 10 for more compact logic practice.

Methodology & sources

The board is a fixed 2 by 3 value array. A legal domino joins uncovered orthogonal neighbors and contributes a previously unused sorted value-pair key. A recursive perfect-matching search tests whether the uncovered remainder is solvable after every placement. Three pairs score 1,200; two invalid selections or an impossible remainder deadlock.

Frequently asked questions

Can the same number pair be used twice?
No. A 1-2 domino and a 2-1 domino are the same unordered pair and may appear only once.
How does the game detect a dead end?
It recursively tests every legal pairing of the uncovered cells using the remaining unused value pairs.
Can I pair diagonal tiles?
No. Dominoes cover exactly two orthogonally adjacent cells.
What is the disclosed solution?
Pair the three vertical columns to create 0-1, 0-2, and 1-2.

Related tools

Mini Games guides

View all