Nurikabe

Each nurikabe here is built by our generator: it grows random islands around an unbroken wall, writes each island's size on one of its squares, and keeps the grid only when the nurikabe solver finds exactly one answer.

Rules

• Every number belongs to an island of unshaded squares with exactly that many squares.
• Each island holds exactly one number. Islands never touch side by side (corners are fine).
• All shaded squares form one connected wall.
• No 2 by 2 block may be completely shaded.

Tap a square once to shade it, twice for a dot that marks it as island, and a third time to clear it; drag to paint a stretch. A 2 by 2 shaded block, or an island with two numbers or too many squares, turns red.

Levels

Easy grids are 5 by 5 with islands of up to 4 squares, medium 7 by 7 with islands up to 5, and hard 9 by 9 with islands up to 6. Hard grids come from a bank we generated and checked, because unique 9 by 9 grids are rare among random ones.

Strategy

• Ones: a 1 is a complete island; shade all four neighbors.
• Between numbers: a square next to two different numbers would join their islands, so it is wall.
• Finished islands: once an island has its size, shade every square around it.
• Unreachable squares: a square that no island can reach with its remaining size must be wall.
• Escape routes: a piece of wall with only one way out must extend that way, or it would be cut off.

Hints and statistics

Hint applies the "between numbers" and "finished island" rules and explains them; when neither applies it reveals one square from the unique answer. Check and Show mistakes compare your shading with the solution; times and the daily streak stay in this browser. Similar shading puzzles: star battle and light up.

Solver tested 6 October 2026. Found a problem? Tell us.

Questions