Nurikabe Puzzle

Nurikabe is a logic puzzle about islands and sea. Shade squares to build one winding stretch of water, leaving each number in an island of exactly that many squares. Every grid is generated by our own code and has one solution.

How to play Nurikabe Puzzle

• Each number belongs to an island of exactly that many unshaded squares. Every island holds exactly one number.
• All other squares are sea and must be shaded. The sea must be one connected area — every shaded square links to the others through edges, not corners.
• The sea may not contain any 2×2 block of shaded squares.
• Islands cannot touch each other side by side; they may meet only at corners.
• Tap a square to shade it, tap again for a dot (a square you know is island), and again to clear. Drag to paint several squares at once.

Controls

• Tap: shade → dot → clear   Right-click or Tap: dot mode: place dots   Drag: paint
• Arrow keys move, Space shade, . or X dot, Backspace clear, Z undo, H hint

Tips

• Every 1 is a single-square island: shade all four of its neighbours straight away.
• A square between two numbers (side by side, or diagonally adjacent across a corner square) must be sea, because islands cannot touch.
• Look for squares no island can reach — they must be sea.
• If three squares of a 2×2 block are shaded, the fourth must be part of an island.
• Keep the sea connected: a shaded square that would be cut off needs an escape route.

FAQ

What are the rules of Nurikabe?

Shade squares so that the unshaded squares form islands, each containing exactly one number equal to its size. All shaded squares must be connected, no 2×2 area may be fully shaded, and islands must not touch along an edge.

How do you solve a Nurikabe puzzle?

Start by shading around 1s and between numbers that are close together. Then find squares that no island can reach and shade them. Use the 2×2 rule and the connected-sea rule to decide the rest, and mark known island squares with dots.

What does Nurikabe mean?

The name comes from a figure in Japanese folklore: an invisible wall that blocks travellers’ paths. In the puzzle, the shaded sea is the wall that winds between the islands.

Does every Nurikabe here have a unique solution?

Yes. Our generator builds a valid grid, places the numbers and keeps the puzzle only if a solver proves exactly one solution exists.

Do I have to place dots?

No. Dots are just notes. The puzzle is solved as soon as the shaded squares are correct.