You're shading a grid into sea and islands. Each numbered cell is an island, and the number tells you exactly how many white cells that island contains — including itself. Paint the rest of the grid black to become the sea, with three rules: every island has precisely its number of cells, the black sea is all connected as one body, and there are no 2×2 blocks of solid black anywhere. Satisfy all three and the hidden landscape appears. There's no guessing — every step can be reasoned.
A fresh daily puzzle each midnight, shareable with a friend through the challenge link.
The two-by-two rule does more policing than any other constraint — the moment a square pool of black threatens, whole regions of the board resolve themselves. Islands must never touch, the sea must stay in one piece, and those three facts together are the entire logic engine. Three difficulty tiers deepen the deductions, the daily grid is shared worldwide, and Suguru Max is the neighbouring region-logic puzzle.
I found Nurikabe while researching new games for the site, and then lost an hour just playing it. That doesn't happen to me often anymore — I test games all day, and the professional reflex is to poke at the edges, note what works, and move on. Nurikabe didn't let me move on. There's something about watching a shapeless grid resolve into islands and sea that bypasses the tester brain entirely, and I knew before the hour was up that it was going on Cliko.
The design call I care most about here is a rendering decision that sounds cosmetic and isn't. The sea — every shaded cell — draws as one continuous colour. No borders between sea cells, no texture breaks, one unbroken dark mass. I chose that because the two illegal states this puzzle produces are both geometric: a pocket of sea that's been cut off from the rest, and a solid 2×2 block of sea. When the sea renders as a single body, a disconnected pool or a forming square is instantly visible to your eye, before you've consciously checked anything. The rule enforcement is in the rendering itself. Your peripheral vision becomes the validator, and it works shifts you didn't assign it.
And you'll need it, because here is the mistake nearly everyone makes, including me in that first hour. Players wall off their islands correctly — each island holding exactly its numbered count of white cells, no two islands touching — and feel the puzzle is basically done. Then the endgame arrives and they discover they've stranded a pocket of sea in a corner, or their last forced shading completes a 2×2 block. Both are illegal, and both were caused twenty moves earlier by decisions that looked free at the time. The island logic is the loud part of Nurikabe. The sea logic is the quiet part that actually decides whether you finish.
So play the sea as a first-class citizen, not as leftover space. Every non-island cell must join one connected, pool-free body of water. When you shade, ask what that shading does to the sea's shape — am I about to pinch off a region? Am I three-quarters of the way to a square? A useful habit: whenever three cells of a 2×2 area are sea, the fourth is forced white, and every forced white cell must belong to some island's count. That single inference, run in reverse, solves entire corners of the board on its own.
Start on the small grids where the sea's whole body fits in your vision at once. The bigger boards are the same game with more patience, and the daily hands everyone the identical grid at midnight. If you lose an hour the way I did, I'll consider the port a success.
The fastest way in is the cells between two islands. Any cell that sits between two different numbered clues must be sea — if it belonged to either island, it would connect them into one, which isn't allowed. Black those in first and you immediately carve up the board. A "1" island is even simpler: it's complete on its own, so every cell touching it is sea.
From there, lean on the two structural rules constantly. The sea has to stay connected, so if blacking a cell would wall off a section of sea into an island of its own, that cell can't be black — it forces a white. And the no-2×2-black rule is a quiet powerhouse: whenever three corners of a square are already black, the fourth is forced white. I bounce between "this must be sea to keep islands apart" and "this must be white to keep the sea legal," and the whole picture resolves without a single guess.
Nurikabe is one of the purest logic puzzles there is — no luck, no guessing, just constraints that force each other until the answer is the only thing left standing. Solving one feels like proving a theorem. I came across Nurikabe while researching games for Cliko, and I fell for it completely. It's a reminder that the Japanese are brilliant at far more than cars and technology — they have a genius for puzzles, for elegant little systems of pure logic, and this is one of the finest. No guessing, no luck, just patience and clear thinking carving an answer out of a blank grid. Falling in love with it taught me to slow down and trust deduction over the lucky leap.
You learn to trust deduction over instinct and to find the move that's certain instead of the one that's tempting — and that a hard problem rewards patience rather than a lucky leap. Bigger grids run the deductions longer. No download, no sign-up — play in your browser on any device. If you like pure logic, try Hashi Bridges next.