Nurikabe

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How to play and about the game

How to play

  1. Each numbered island has exactly as many cells as its number.
  2. The black cells form one connected river with no 2×2 block.
  3. Two islands never touch along an edge.

Controls

Pick Black, White or Clear, then tap a cell. Keyboard: arrows move, 1 black, 0 white, Backspace clears, H hint, U undo.

About this game

A 30-level campaign on 5×5 to 9×9 boards, plus a daily puzzle. Every island holds exactly its number, the black river stays connected with no 2×2 block, and each level has one solution.

  • 5–9 min
  • Single player
Levels
30, 5×5 to 9×9
Solution
Unique, solver-checked
Help
Hint, undo

Strategy and tips

Four steps from your first game of Nurikabe to expert play.

  1. First game

    A 1 is one white cell, so every neighbour it has is black: four in the middle, fewer on an edge or corner.

  2. Getting better

    A single cell between two numbers must be black. If it were white, it would join both islands.

  3. Confident

    An island that already holds its full count is finished, so every cell touching it must be black.

  4. Expert

    No four black cells may form a square. When three of them are already black, the fourth must belong to an island.

Common mistake Painting a cell black only because it looks empty. A wrong move is not applied and counts as a mistake; five end the attempt.