New: Kerb Clash, clear the jammed car parkNew: Sudoku and Minesweeper, classic puzzles that play offlineInstall any game to your home screen

Hitori Rules: How to Play (With Examples)

Hitori is a logic puzzle where you shade squares on a grid of numbers. The aim: no number appears twice in a row or column among the unshaded squares. Two more rules keep it honest: shaded squares can’t touch side by side, and the unshaded squares must all stay joined up. The name is Japanese for “alone”.

Open Hitori full screen for more sizes, saved progress and best times.

The rules

Shade squares so that:

  1. No number appears twice in a row or column among the unshaded squares.
  2. Shaded squares never touch side by side. Corner to corner is fine.
  3. The unshaded squares all join up into one piece, side by side.

When all three hold, the puzzle is solved. You can also circle a square to mark it as sure to stay unshaded.

What breaks a rule

The same number twice, unshaded. Both 3s in this top row are left unshaded, so one of them has to go:

The same number twice, unshaded: not allowed A 3 by 3 grid with both 3s in the top row left unshaded (ringed in red). One of them must be shaded. 3 1 3 2 2 3 1 3 1
Two unshaded 3s in the same row (ringed): not allowed.

Shaded squares side by side. These two touch:

Shaded squares side by side: not allowed A 3 by 3 grid with the first two squares of the middle row shaded, touching each other. 3 1 3 2 2 3 1 3 1
Two shaded squares touching (ringed): not allowed.

An unshaded square cut off. These two shaded squares don’t touch each other, but they wall in the top-left corner, cutting it off from the rest:

An unshaded square cut off: not allowed A 3 by 3 grid with the top-middle and middle-left squares shaded. They don't touch each other, but they wall in the top-left square, cutting it off from the rest. 3 1 3 2 2 3 1 3 1
The top-left square (ringed) is cut off from the other unshaded squares: not allowed.

In the game, a repeated number turns red, touching shaded squares get a red outline, and a finished grid that’s split gets a red frame.

A puzzle from the game, solved

This is the first level in the game: Easy level 1, a 5×5.

Easy level 1 from the game A 5 by 5 Hitori. Rows: 3 1 4 5 5; 5 4 2 1 3; 3 2 4 4 1; 3 3 5 4 1; 4 2 4 3 5. 3 1 4 5 5 5 4 2 1 3 3 2 4 4 1 3 3 5 4 1 4 2 4 3 5 1 2 3 4 5 1 2 3 4 5
Easy level 1, before you start. Rows and columns are numbered from the top left.

It takes 14 steps, using three ideas. Here are the first three.

Step 1: a sandwich

Row 5 starts 4 2 4: a 2 between two 4s. If the 2 were shaded, neither 4 could be (shaded squares can’t touch), so both 4s would stay unshaded, and repeat. So the 2 stays unshaded. Circle it.

Step 1: a sandwich in row 5 Row 5 starts 4 2 4. If the 2 were shaded, both 4s would have to stay unshaded, and they would repeat. So the 2 stays unshaded, and is circled. 3 1 4 5 5 5 4 2 1 3 3 2 4 4 1 3 3 5 4 1 4 2 4 3 5 1 2 3 4 5 1 2 3 4 5
Row 5: the 2 between two 4s stays unshaded.

Step 2: its twin is shaded

The circled 2 stays unshaded, so no other 2 in its row or column can. Column 2 has another 2, in row 3: shade it.

Step 2: the 2 in column 2 repeats The circled 2 in row 5 stays unshaded, so the other 2 in its column, in row 3, must be shaded. 3 1 4 5 5 5 4 2 1 3 3 2 4 4 1 3 3 5 4 1 4 2 4 3 5 1 2 3 4 5 1 2 3 4 5
The circled 2 means the other 2 in column 2 is shaded.

Step 3: around the shaded square

Shaded squares can’t touch, so the four squares beside the new shaded one all stay unshaded. Circle them.

Step 3: around the shaded square The shaded square in row 3, column 2 can't touch another shaded square, so the four squares beside it stay unshaded. 3 1 4 5 5 5 4 2 1 3 3 2 4 4 1 3 3 5 4 1 4 2 4 3 5 1 2 3 4 5 1 2 3 4 5
The four squares beside the shaded one stay unshaded.

The rest

Those two moves, over and over, finish the grid: every circled number shades its twins, and every shaded square circles its neighbours. In all it takes 1 sandwich, 5 repeats and 8 rounds of circling neighbours.

Easy level 1, solved The finished grid: eight shaded squares, none touching, no number repeated among the rest in any row or column, and all the unshaded squares joined up. 3 1 4 5 5 5 4 2 1 3 3 2 4 4 1 3 3 5 4 1 4 2 4 3 5 1 2 3 4 5 1 2 3 4 5
Easy level 1, solved: eight shaded squares.

Where to start in any puzzle

Look for a sandwich: a number between two of the same, like 4 2 4. The middle one stays unshaded. Every one of the game’s 150 levels has at least one on the empty grid, so it’s always a way in. Also look for two alike side by side with a third copy elsewhere in the line: one of the pair must stay unshaded, so the third copy is shaded. Most levels have one of those too: 38 of the 50 Easy levels, 43 Medium and 37 Hard.

Common mix-ups

  • Shaded squares can touch at the corners. Only side by side is against the rules.
  • Only unshaded squares count for repeats. A shaded square’s number doesn’t matter any more.
  • Joined up means side by side. Two unshaded squares that only meet at a corner aren’t joined.

Next steps

Questions

What does Hitori mean?

It’s Japanese for “alone”: every number left unshaded is alone in its row and column.

What are the circles for?

Marking squares you know will stay unshaded. They’re not part of the answer, but they help: a circled number’s twins in its row and column must be shaded.

Does every puzzle have one solution?

Yes. Every puzzle on PeerPuzzles has exactly one solution, and can be finished by logic alone, without guessing.

Can I shade a number that isn't repeated?

The rules allow it, as long as all three still hold. But in every one of the game’s 150 levels, each shaded square has the same number left unshaded somewhere in its row or column, so a number that doesn’t repeat is never one you need to shade.

What size should I start with?

5×5. Every Easy level starts with a sandwich, a number between two of the same, which gives you a sure first move.