Nurikabe

How to play nurikabe online

1. Set the Size to 5×5, 6×6, 7×7 or 10×10. The default is 7×7.
2. Set the Difficulty to Easy, Medium or Hard.
3. Click New puzzle. “Generating…” shows while the board is made, and the puzzle is ready when it appears.
4. Click or tap a cell to shade it as wall. Click it again to clear it.
5. Right-click, or use the Dot chip, to mark a cell as island (unshaded).
6. If you are stuck, click Hint. It highlights the cells involved and explains in one sentence which rule proves the next step.
7. Click Check to see cells that break a rule or differ from the solution, shown in red. It also says “No mistakes so far” with the percentage done.
8. When the page says “Solved in m:ss”, it shows how many hints you used. Choose Next puzzle to continue.

Keyboard controls: arrow keys move, Space shades, X marks a dot, and Backspace clears. Undo and Redo work with Ctrl+Z and Shift+Ctrl+Z (Cmd on a Mac). Restart clears the board but keeps the same puzzle. Copy link saves the size, seed and difficulty in a link, so the same puzzle opens on another device. On a phone, the Wall, Dot and Move chips above the board choose what a tap does.

Nurikabe rules

Nurikabe is a Nikoli puzzle. Some cells hold numbers, and you shade cells to form the wall. The name comes from a wall spirit in Japanese folklore. The rules are:

• Every number sits in an island of unshaded cells of exactly that size.
• Each island holds exactly one number.
• All shaded cells form one connected wall, joined orthogonally (up, down, left or right).
• The wall never contains a 2×2 block of shaded cells.

A 1 is a one-cell island, so every neighbour of a 1 must be wall.

How to solve nurikabe

You solve a nurikabe puzzle by applying the rules one step at a time, starting with the simplest deductions. The tool’s solver groups its techniques into three levels of difficulty.

Easy puzzles need six techniques. Touch makes a cell between two islands wall. Full makes the neighbours of a finished island wall. Pool forces the fourth cell of a 2×2 block to be unshaded when three of its cells are wall. Exit makes a too-small island grow in its only possible direction. Wallexit sends a loose piece of wall to its only possible join. Far makes wall of any cell that no number can reach.

Medium puzzles add three more. Bridge makes a cell wall if leaving it unshaded would split the wall in two. Forced makes a cell unshaded when every route to a number must pass through it. Shapes lists every final shape a small island can take, then marks cells in all shapes as island and cells in no shape as wall.

Hard puzzles need trial. You assume a cell has one state, follow the consequences, and if you reach a contradiction, the cell must be the other state.

For example, in the 5×5 Easy puzzle with seed 3, the first hint says: “Row 1, column 4 touches two different islands (or joining would make an island too big), so it cannot be unshaded. Shade it.” This is the touch technique at work.

Frequently asked questions

What is a nurikabe puzzle?

A nurikabe puzzle is a grid with numbers in some cells. You shade cells to build one connected wall, so that each number is surrounded by an unshaded island of exactly its size. Every puzzle here has exactly one solution, so logic can always finish it.

Is nurikabe free, and do I need an account?

Yes, it is free, and there is no account or sign-up. Progress and settings are saved automatically in your browser and restored when you come back. Nothing is uploaded.

Can I play nurikabe on a phone?

Yes. The board works on phones, tablets and computers. On a phone, use the Wall, Dot and Move chips above the board. Choose Fit to fit the board to the screen width, or use Zoom in and Zoom out to change its size.

Can I print a nurikabe puzzle?

Yes. Click Print, and the puzzle prints on its own page with its size, difficulty and the rules. Tick “Print the answer page too” to add the solution on a second page. In the print dialog, you can choose “Save as PDF”. A4 and Letter paper both work.

Does every nurikabe puzzle have one solution?

Yes, on this page. Each puzzle is generated in your browser and kept only when the site’s solver proves it has exactly one solution. This means logic alone can finish it, and you never have to choose between two answers.

Can I turn off the rule-error warnings?

Yes. “Show rule errors as I play” is on by default and marks rule breaks in red as soon as they appear. Turn it off if you want a harder game, then use Check when you want to test your board.

Can I use nurikabe puzzles from this page in a KDP puzzle book?

Yes. Nurikabe puzzles from this page are royalty-free for personal, classroom and commercial use, including Amazon KDP puzzle books, Etsy printables, Teachers Pay Teachers and print-on-demand products. No credit is required. The only thing you may not do is copy the generator or the site itself to run a competing service; see the terms.

Related tools

• Star Battle: Use it for another grid puzzle where you place stars under row, column and region limits.
• Shikaku: Try it if you enjoy dividing a grid into rectangles that each hold one number.
• Norinori: Choose it for a shading puzzle that also follows region and pairing rules.
• Slitherlink: Play it if you like drawing one loop that matches the clue numbers.
• Bridges puzzle (Hashi): Use it for another island puzzle, where you connect numbered islands with bridges.
• Binary puzzle (Binairo): Try it for a grid of 0s and 1s that follows balance rules.
• Mosaic puzzle: Choose it for a shading puzzle where numbers tell you how many neighbouring cells are shaded.
• Nonogram (play online): Play it if you want to solve pictures from row and column clues.
• Tapa puzzle: Play it to build one connected wall from clues that describe the shaded runs around them.