Score
0
Time
90s
Best
—
A bite-size island-and-sea logic puzzle from Japan, named after a wall spirit. On a small 5×5 grid, some cells hold numbers. Shade the rest into a single connected 'sea' so that each number sits in its own white 'island' of exactly that many cells. Islands may never touch side by side, and the sea can never form a full 2×2 block. Solve as many boards as you can in 90 seconds.
Tap any blank cell to shade it into the sea; tap it again to clear it back to land. The numbered cells are fixed — they are always part of an island and can't be shaded.
You are solving for four things at once: every number must be the size of the connected white island it belongs to; each island must contain exactly one number; no two islands may share an edge (a diagonal touch is fine); all the shaded sea must be a single connected region; and the sea must never contain a 2×2 square of four shaded cells.
The moment your shading satisfies all of that, the board is solved, you score a point, and a fresh puzzle appears. There is no need to press a button — the game checks after every tap.
Solve as many boards as you can before the 90-second clock runs out. Your score is the number you complete; beat your best and save it to the Hall of Fame.
Start from the numbers, not the blanks. A clue of 1 is an island all by itself, which means every cell touching it — up, down, left and right — must be sea. Shading those in first is free, certain progress, and it often chains: those forced sea cells reveal more forced sea, and the board unwinds itself.
The cells between two clues are almost always sea. Two different islands can never touch side by side, so any single blank cell wedged directly between two numbers must be shaded — otherwise it would join them into one island with two clues, which is illegal. Look for those pinch points early.
Watch the sea's shape, not just its cells. Two rules quietly constrain every shading: the sea must stay one connected piece, and it must never fill a full 2×2 square. When you are about to shade a cell that would complete a 2×2 block, one of the other three cells in that square has to be an island instead — and that often tells you exactly where an island must extend.
Count an island's escape routes. A clue of 3 needs two more white cells beyond itself, all connected. If it can only grow in one direction, that direction is forced; if surrounding sea has already boxed it into a space too small, you have made a mistake earlier. Growing islands and flooding sea are two sides of the same deduction — each cell you assign to one side removes a possibility from the other.
In the timed game, speed comes from the 1s and the tight corners. Sweep the board for lone clues and between-clue pinches, shade all the certain sea in a burst, and only then reason about the larger islands. A 5×5 board that looks blank is usually two or three forced moves from solving itself.