How to play Hitori
Shade cells so no number repeats in a row or column, shaded cells never touch, and the rest stay connected.
The rules
- The grid starts full of numbers.
- Shade some cells so that no number appears more than once among the unshaded cells of any row or column.
- Shaded cells may not touch each other side to side (diagonal is fine).
- All unshaded cells must form one connected group, joined side to side.
Playing Hitori on Puzzle Solvers
- Pick a grid size and difficulty and press New Puzzle.
- Click a cell to shade it; click again to clear it. Right-click or long-press to mark a cell you are sure stays unshaded.
- Undo, Hint and Check are on the toolbar; the Progress panel counts shaded cells and rule violations.
- Send to Solver shows the full solution step by step; Send to Slate puts the puzzle on a Slate whiteboard.
Using the Hitori solver
- Choose a grid size and type the numbers from your puzzle (or press Random).
- Press Solve: the solver shades the cells and lists its deductions.
- After solving, click a cell to toggle its shading and explore.
A worked example
A row reads 3 1 3 4. Of the two 3s, one must be shaded. If the 1 between them were shaded, neither 3 could be (they would touch the shaded 1), leaving two 3s unshaded. So the 1 stays unshaded.
Now suppose the first 3's column already has another unshaded 3: then that 3 must be shaded, its neighbours stay unshaded, and the second 3 in the row is safe.
Strategies
- Sandwiches. In a pattern like 2 5 2 in a row, the middle 5 can never be shaded: one of the 2s must be shaded, and shading 5 as well would leave both 2s unshaded.
- Adjacent twins. If two equal numbers sit side by side, one of them is shaded — so every other copy of that number in the same row must be shaded.
- Circle the safe cells. Every neighbour of a shaded cell must stay unshaded. Mark those cells (right-click or long-press in the game).
- Keep it connected. Never shade a cell that would cut the unshaded area in two — that is often the deciding clue late in a puzzle.
- Unique numbers. A number that appears only once in both its row and its column never needs to be shaded.
Common mistakes
- Shading two cells that share an edge.
- Forgetting the connectivity rule until the end — check it as you go.
Where it comes from
Hitori ('alone' in Japanese) was introduced by a Japanese puzzle publisher in 1990.
Frequently asked questions
What does right-click do in the Hitori game?
It places a circle — a note that a cell must stay unshaded. Long-press does the same on a phone or tablet.
Do shaded cells need to be connected?
No — the unshaded cells must be connected. Shaded cells must not touch at all.
Can I paste a puzzle into the solver?
Enter the numbers in the Hitori Solver grid (or press Random) and click Solve to see the shading and the reasoning.
Keep going
- Play Hitoria fresh puzzle every time
- Hitori Solverstep by step, every move explained
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- SudokuFill the grid so every row, column and box contains each digit exactly once.
All guides: How to play every puzzle and game.