How to Play Nurikabe: Rules, Strategy & Free Puzzles
Nurikabe is a shading puzzle. You colour cells to form the "sea" while leaving white "islands" behind. Each numbered cell is part of an island of exactly that many white cells, every island is kept separate from the others, the sea is all connected, and the sea never contains a filled 2×2 block.
- Skill: Region logic & connectivity
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- Difficulty: Advanced
How to play Nurikabe
- Islands match their number. Each numbered cell belongs to a white island whose size equals that number.
- One clue per island. Every island holds exactly one number; islands never touch edge to edge.
- The sea is connected. All shaded cells join into one continuous sea.
- No 2×2 sea. The shaded sea may never form a solid two-by-two square.
Nurikabe strategy & tips
- Cells between two different island clues must be sea — islands cannot merge.
- A completed island must be walled off entirely by sea, which reveals forced shaded cells.
- Watch the no-2×2 rule: it often forces a single white cell that must belong to a nearby island.
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Nurikabe FAQ
What do the numbers mean in Nurikabe?
Each number is the size, in cells, of the white island it sits on. A 3 marks an island of exactly three connected white cells.
Can the sea form a solid block?
No. The shaded sea must stay connected but can never fill a complete 2×2 square anywhere on the board.
Related puzzles
Reference: Nurikabe on Wikipedia