TappyPotato logic puzzles

Pencil logic

Nurikabe — rules and where to play

NURIKABE · Islands in the Stream / Cell Structure

Digits are islands, everything else is sea. You decide which cells sink, while keeping the sea one connected body and the islands apart.

Origin
1991 · Japan
Difficulty
★★★★★ 3–5 / 5
Time
10–60 min
Grid
7×7 – 25×25
Sites
10

Rules

  1. Each numbered cell belongs to an island whose size equals the digit.
  2. Islands may touch only diagonally, never edge to edge.
  3. All black cells (the sea) must form one connected region.
  4. No 2×2 block of black cells is allowed.

How to start

Close off completed islands first

The moment an island hits its number, blacken all four of its sides. It is the most reliable opening move.

Use "the sea is connected" as a weapon

If blackening a cell would cut the sea in two, that cell is white. In the middle game this fires almost every step.

Run the 2×2 ban as a scanner

Any cell that would complete a 2×2 black square must be white. One sweep can settle a whole region.

Where players get stuck

  • Forgetting the sea must stay connected, then ending with two seas staring at each other.
  • Merging two equal digits that sit next to each other — only cells actually joined count as one island.

Play Nurikabe

10 sites
Puzzle PicnicFree

Handmade Nikoli-style grids from a mix of setters, picked rather than dumped, playable in the page.

Open → PuzzleMixFreemium

Gareth Moore's site: Sudoku, then Slitherlink, Nurikabe, Futoshiki, Calcudoku and Hanjie.

Open → pzv.jpFree

A wider puzz.link-style database — more types, cut a bit finer.

Open → Penpa+Free

A fat editor for Japanese types: lots of shapes and marks, and it will ingest a puzz.link.

Open → pzplusFree

A community bank with difficulty and clear counts, browsable without leaving the page.

Open → Naoki InabaFree

Naoki Inaba writes a lot, including types you won't see many other places.

Open → Puzzle Square JPFree

A large Japanese variant archive that moves often, with difficulty marks on the grids.

Open → Grandmaster PuzzlesFree

Thomas Snyder's own handmade Sudoku and variants — world-champion difficulty, not generated filler.

Open → Puzzle-NurikabeFree

Puzzle Team's Nurikabe specialty: a daily, a deep bank, same UI family as their other grids.

Open → GridPuzzleFree

Dozens of grid logic types in the browser, with progress tracking and dailies.

Open →

Browse Japanese pencil puzzles →

Also on multi-type portals

Janko.atFree

Otto Janko's German/English archive: hundreds of playable types, all free.

Open → Puzzle RulesFree

Clean rule pages for dozens of types. Fastest way to learn a grid you haven't seen.

Open → NoqxFree

An ASP solver for 170-plus types. Connectivity puzzles tend to come back quickly.

Open → Nikoli Puzzle SolverFree

Z3 under the hood, 100-plus types, including hex and triangle boards.

Open →

Browse portals →

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About this page
  • Last updated 2026-09-22
  • Source Curated compilation of established puzzle rules and listed third-party play sites
  • Audience Players learning Nurikabe rules or looking for online sites to play
  • Covers Rules summary, how to start, common pitfalls, and the dedicated play sites listed on this page
  • Does not cover Hosted puzzles, worked solutions, official contest rankings, third-party uptime or pricing guarantees
  • Not advice This page is puzzle reference content only. It does not constitute financial, legal, medical or other professional advice.
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