What is Nurikabe?
Nurikabe is a Japanese logic puzzle about separating numbered islands with one continuous wall. Each number belongs to a white island, and the value tells you exactly how many cells that island must contain.
This free Nurikabe online game lets you play 6x6, 8x8 and 10x10 grids on easy, medium and hard difficulty. Every puzzle in the game bank has been checked for a single solution, so you can solve by logic rather than guessing.
- Shade cells to build the black wall.
- Leave white island cells connected to exactly one number.
- Each island must contain as many cells as its clue number.
- Different islands may not share an edge, but diagonal corner-touching is allowed.
- The wall must be one connected shape with no 2 x 2 black square.
How to play Nurikabe online
Click or tap an empty cell to shade it as wall, then tap the same cell again to clear it. Numbered clue cells are already island cells and cannot be shaded.
Use Check whenever you want feedback without revealing the answer. Hint adds a correct wall cell or clears an incorrect wall cell, Solution shows the full board, and New puzzle loads another uniquely solved Nurikabe challenge for the same size and difficulty.
- Start around 1 clues because a one-cell island is already complete.
- Mark wall cells between two different numbered islands.
- Watch for 2 x 2 wall blocks; they are never allowed.
- Keep the black wall connected as it grows.
- Use island sizes to decide which nearby cells must stay unshaded.
Nurikabe rules
The core Nurikabe rules are simple, but they interact across the whole grid. White cells form islands. Black cells form the wall. The wall is not allowed to split into separate areas, and islands are not allowed to merge.
A completed board has every non-numbered white cell attached to one clue by side-adjacency only. Diagonal cells do not connect. If an island has a 3 clue, exactly three orthogonally connected white cells belong to that island, including the clue cell itself.
- A number is part of its island.
- An island has exactly one number.
- Two islands cannot share an edge.
- Diagonally touching islands stay separate.
- All black cells connect orthogonally.
- No 2 x 2 area may be fully black.
Nurikabe strategy tips
Good Nurikabe strategy starts by looking for forced walls. A completed island must be surrounded by wall or board edges, and two different islands need wall cells between them.
As the puzzle gets harder, wall connectivity becomes the main strategic pressure. If shading a cell would isolate part of the wall or create a forbidden 2 x 2 block, that cell must stay white.
- Surround every completed island.
- Put a wall between adjacent island frontiers from different clues.
- Use 2 x 2 prevention to force island cells.
- Avoid closing off an unconnected black area.
- Count island growth carefully before marking speculative white cells.
Nurikabe grid sizes and difficulty
Small Nurikabe puzzles are ideal for learning the island and wall rules. Larger grids give the wall more room to twist, which makes connectivity and 2 x 2 prevention more important.
Easy boards have more local deductions. Medium boards ask you to combine island counting with wall growth. Hard Nurikabe puzzles use larger boards and longer chains of consequences, but each puzzle still has one solution.
- 6x6 Nurikabe is a friendly starting grid.
- 8x8 Nurikabe gives a balanced online puzzle challenge.
- 10x10 Nurikabe adds more strategic wall planning.
- Easy, medium and hard change clue shape, island size and deduction pressure.
- Board rotations and flips add variety while preserving unique solutions.