Play Dominosa Online — Free
A complete set of domino pieces is hidden in the grid. Determine which cells form each domino without using any piece twice.
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About Dominosa
Dominosa is a deduction puzzle built from a complete set of dominoes. A rectangular grid is filled with numbers, and your task is to recover the exact placement of every domino from the full set — each domino (a pair of numbers) appears exactly once, and together the dominoes tile the entire grid.
The key insight is uniqueness: if a number pair appears only once in the grid as adjacent cells, that pair must be the domino with those two values. Finding these forced dominoes immediately eliminates those number pairs as candidates for all other adjacent cells, triggering further deductions in a satisfying cascade.
Dominosa is underrated among logic puzzles. It requires no domain knowledge, scales easily to harder sizes (larger sets of dominoes = harder puzzles), and the satisfying click of placing all dominoes correctly is deeply rewarding. It’s an excellent choice for puzzle fans looking for something off the beaten path.
Keep a matrix of which domino values have been placed and which remain. When only one pair of adjacent cells in the grid can still accommodate a remaining domino value, that placement is forced — this is the equivalent of a “hidden single” in Sudoku.
Frequently asked questions
What is Dominosa?
Dominosa presents a grid of numbers that contains a complete set of dominoes. Your task is to draw borders around the dominoes to show where each piece is placed. Every domino in the set appears exactly once.