Hitori
Shade cells to eliminate duplicate numbers in every row and column.
Rules
- No duplicates: No number may appear more than once in any row or column among the unshaded (white) cells.
- No adjacent shading: No two shaded cells may share an edge. Diagonal contact is fine.
- White connectivity: All unshaded cells must form a single orthogonally connected region.
The puzzle is solved when all three rules hold simultaneously.
Controls
| Key | Action |
|---|---|
Arrows / wasd / hjkl |
Move cursor |
Mouse left-click |
Focus a cell |
x |
Toggle shade on cell |
z |
Toggle circle (confirmed white) |
Backspace |
Clear cell to unmarked |
Ctrl+H |
Toggle full help |
Ctrl+R |
Reset puzzle |
Escape |
Return to main menu |
Tips
- Circle the unique numbers first. If a number appears only once in its row and column, it can never be shaded. Circling these cells gives you safe anchors to reason from.
- Watch for forced shading. When a number appears twice in a row or column and one copy is already circled, the other copy must be shaded.
- Protect connectivity. Before shading a cell, check whether it would split the white region into disconnected pieces. Cells that act as bridges between unshaded areas should almost always stay white.