How to play Domino Shade
Shade exactly two squares in every region so the shaded squares form dominoes that never touch side to side. Also known as Two-per-region shading, Domino region puzzle.
The rules
- The grid is divided into regions.
- Shade exactly two squares in every region.
- Every shaded square shares a side with exactly one other shaded square — together they form a domino.
- A domino may lie inside one region or cross from one region into the next. Dominoes may touch at corners, but never along a side.
Playing Domino Shade on Puzzle Solvers
- Choose a size and a difficulty, then press New Puzzle.
- Tap a square to shade it, again for a dot (white), again to clear. Drag to do several; right-click places a dot.
- Squares break the rules turn red — three shaded in a region, or a shaded square touching two others.
- Hint explains the next deduction — regions that only fit one way, dominoes that would touch, and regions working together.
Using the Domino Shade solver
- Choose the size and draw the regions (or press Sample).
- Press Solve and step through: regions with few ways, dominoes that would touch, and pairs of regions together.
A worked example
A region of two squares in the corner is a whole domino, so the squares touching it along their sides are white.
A region of three squares in an L: shading the two ends would leave them unpaired unless each has a partner outside — check which neighbours are still free.
Strategies
- Tiny regions. A two-square region is a domino. A straight three-square region has its middle square shaded.
- Around a domino. Once a domino is finished, every square touching it along a side is white.
- Lonely squares. A shaded square with only one possible partner must pair with it.
- Two regions together. When two small regions sit side by side, try the few ways each can be shaded — often only some combinations keep the dominoes apart.
- Count what is left. A region that already has two shaded squares is finished — dot the rest.
Common mistakes
- Leaving a shaded square with no partner, or with two.
- Letting two dominoes touch along a side.
- Forgetting a domino can cross a region border.
Where it comes from
Region-shading puzzles with two squares per region were made famous by Japanese puzzle magazines and are popular in puzzle collections worldwide.
Frequently asked questions
Can a domino cross from one region to another?
Yes — each square still counts for its own region.
Can dominoes touch diagonally?
Yes, at corners only.
Is there always one answer?
Yes — every puzzle here is checked to have exactly one solution.
How do I solve one from a book?
Open the Domino Shade Solver, draw the regions and press Solve.
Keep going
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