⬛ Hitori

A logic puzzle where you shade duplicate numbers black. Black cells cannot be adjacent, and white cells must all be connected. 3 difficulty levels with 5+ puzzles each.

time
0:00
Miss
0
3
Left-click → Black
Black cell (shaded)
?
Right-click/Double-click → Mark

Rules and Controls

Rule 1: No DuplicatesIf the same number appears twice in the same row or column, shade one black. No duplicate numbers should remain as white cells.
Rule 2: No Adjacent Black CellsBlack cells cannot be adjacent horizontally or vertically. Diagonal adjacency is allowed.
Rule 3: Connected PathAll white cells must be connected horizontally and vertically. No isolated white cells are allowed.
How to operateLeft-click: Toggle between white → black → white. Right-click/Double-click: Toggle "?" mark (uncertain indicator).

What is Hitori?

Hitori is a Japanese logic puzzle offering fresh appeal to fans seeking alternatives to Sudoku. Fill the grid so no row or column contains duplicate numbers, while keeping all white cells connected and ensuring black shaded cells never touch each other horizontally or vertically. Available in multiple difficulty levels, Hitori challenges logical reasoning and spatial awareness through elegant rule simplicity combined with deductive complexity.

How to Use

Click cells to toggle between three states: numbered, shaded black, or marked unsure. Study the puzzle rules carefully: shade one copy of duplicate numbers in each row and column to achieve uniqueness. Ensure shaded cells never touch horizontally or vertically—diagonal contact is permitted. Maintain white cell connectivity throughout the grid so you can reach every white cell without jumping over shaded cells. Solve systematically by identifying forced moves first. Mark uncertain cells and refine answers progressively. Submit your complete solution when confident, or use reset to clear mistakes and restart.

Use Cases

Daily puzzle enthusiasts solve one Hitori puzzle as a morning mental warm-up and brain exercise. Teachers incorporate Hitori in classroom lessons to develop logical reasoning skills across age groups. Puzzle game developers feature Hitori alongside other puzzles to offer diverse gameplay experiences. Cognitive training and brain health programs include Hitori as mental exercise for all ages. Travelers and commuters play offline Hitori when seeking engaging digital entertainment. Therapists recommend Hitori for cognitive rehabilitation, mental focus improvement, and therapeutic engagement.

Tips & Insights

Hitori develops different cognitive skills than Sudoku—pure deduction rather than mathematical reasoning. Start by identifying rows and columns containing multiple duplicates; shading obvious duplicates constrains future choices significantly. The white-cell connectivity rule proves powerful for logical deduction and eliminates impossible shading patterns. Advanced solving sometimes requires working backward—assuming a solution path and revealing contradictions. Unlike Sudoku where each number appears exactly once, Hitori specifically uses duplicates as the core puzzle element driving solution logic.

Frequently Asked Questions

What are the rules of Hitori?

There are 3 rules. ① Shade duplicate numbers in the same row or column so no duplicates remain. ② Black cells cannot be adjacent horizontally or vertically. ③ All white cells must be connected in a single path.

How do I operate the cells?

Left-click to shade a cell black, right-click or double-click to toggle a "?" mark (uncertain indicator). Click again to return to white.

How are rule violations displayed?

When a rule violation occurs, related cells are highlighted in red. This includes white cells with duplicate numbers in the same row or column, adjacent black cells, and disconnected white cells.

What is the difference in difficulty level?

Easy is 6×6 grid, Medium is 8×8 grid, Hard is 10×10 grid. Larger grids require more complex logical reasoning. 5+ built-in puzzles for each difficulty level.

Is there an undo button if I make a mistake?

Yes, use the Undo button or right-click on cells to remove marks. You can also restart the puzzle anytime to try again from the beginning.

Can I save my progress and come back to it later?

Many versions auto-save using browser storage. Check if an in-progress puzzle loads when you return to the page, or manually note your moves to resume later.

Are the puzzles generated randomly or pre-set?

Most versions include pre-generated puzzles of varying difficulty. Each session typically shows different puzzles, though some may use a fixed set.

How long should a typical puzzle take to solve?

Easy puzzles typically take 2-5 minutes, Medium 5-15 minutes, and Hard 15-30+ minutes depending on your strategy and experience level.

Can I print a puzzle to solve on paper?

Many versions have a Print button for solving on paper. If not, take a screenshot and print it, though interactive solving in the browser is usually easier to track moves.

Do different difficulty levels have different grid sizes?

Typically all puzzles use the same grid size (like 8×8), but difficulty increases through puzzle complexity and fewer starting clues. Some advanced versions may offer 10×10 or 12×12 grids.