Nurikabe 塗壁

Logic · 600 levels in the app

A grid deduction puzzle where you shade cells to form a connected "river" of black cells, while every number on the board defines the exact size of its white island: islands must never touch each other.

How to play

Tap an empty cell to shade it black (river). Tap a black cell to turn it white again. Each numbered cell is the seed of an island; the number tells you exactly how many white cells that island contains. Islands cannot touch horizontally or vertically. All black cells must form one connected group, and no 2×2 block of black cells is allowed.

Objective

Shade exactly the right cells so every island matches its number, no two islands touch, and all black cells form one connected river.

Strategy tips

1. Mark cells that are clearly river first: any cell not reachable by any island's number belongs to the river. Working from the "impossible" cells inward is faster than guessing from scratch.
2. Islands of size 1 (a single cell) are already complete: immediately shade all four of their neighbours as river.
3. If two adjacent islands together can't reach a gap cell without touching each other, that gap must be river. Use this "pinch" logic to resolve ambiguous regions.

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