Nurikabe Variants: Beyond the Classic Island Puzzle

Most logic puzzles have a handful of variations at best. Nurikabe has a small empire of them. Over the years, puzzle designers have taken the basic idea, build islands in a connected sea, and twisted it in a dozen clever directions: changing the shape of the islands, hiding the clues, wrapping the grid around itself, even relaxing the rules about touching. If you have mastered classic Nurikabe and want to know how deep the rabbit hole goes, this is your tour of the most interesting Nurikabe variants and what makes each one tick. First, if you are still warming up on the original, you can play classic Nurikabe any time.

A quick refresher on classic Nurikabe

Before the variants, the original. In standard Nurikabe you shade cells to build a single connected black "sea" around white "islands." Each numbered cell sits in an island whose size matches the number, islands cannot touch each other side by side, the sea must all connect into one region, and no 2×2 block may be entirely black. Almost every variant below keeps that skeleton and changes one or two bones. (New to the rules? Our how-to-play guide covers them.)

The close family: Nuribou, Mochikoro and Mochinyoro

The puzzles most often grouped with Nurikabe are its direct cousins, sometimes called the "paint" or coloring family.

• Nuribou ("paint the stick") swaps islands for straight strips. Instead of blobs of a given area, the white clues form straight horizontal or vertical "sticks" of a given length, while the black region still has to stay connected and avoid 2×2 pools. It feels like Nurikabe with a ruler.
• Mochikoro changes the connectivity rules: the white cells must connect (not the black), and it is the white regions that avoid 2×2 blocks. It is almost a photo-negative of Nurikabe.
• Mochinyoro blends ideas from both, combining connected white regions with stick-like constraints.

If you adore Nurikabe specifically, these three are the puzzles that feel most like home, with just enough of a twist to surprise you.

Shape variants: pentomino and domino Nurikabe

Some variants fix what shape the islands must take.

• Pentomino Nurikabe requires every island to be a pentomino (a five-cell shape), which removes the size numbers and replaces them with a shape constraint. You are no longer told how big each island is, only that each must be one of the classic five-cell shapes.
• Domino Nurikabe and similar shape variants impose other fixed forms on the islands or the sea.

These versions shift the puzzle from "how big" to "what shape," which changes your deductions completely.

Clue twists: coded, cipher and Araf

Other variants keep the islands but mess with the clues.

• Coded or Cipher Nurikabe replaces the numbers with letters, where each letter stands for an unknown size you must deduce, adding a layer of code-breaking on top of the logic.
• Araf (and its relative Nuraf) gives each region a range of sizes rather than an exact number, or places two numbers that a region's size must fall between, loosening the tidy "island size equals the number" rule into something fuzzier and trickier.

Rule relaxations: No Touch and All Ones

A few variants change the structural rules themselves.

• No Touch Nurikabe tightens island separation, forbidding islands from touching even diagonally, not just orthogonally.
• All Ones and similar versions fix every island at a single size, turning the puzzle into a pure placement-and-connectivity challenge with no size variety.

Grid twists: toroidal Nurikabe

Finally, some variants change the board rather than the rules. Toroidal Nurikabe wraps the grid around itself, so the left edge connects to the right and the top to the bottom, like the surface of a doughnut. Islands and the sea can flow off one side and reappear on the other, which makes connectivity reasoning genuinely mind-bending.

Why explore the variants?

The wonderful thing about the Nurikabe family is how one elegant idea, a connected sea around sized islands, supports so many directions. Each variant keeps the core pleasure of shaping black and white regions while teaching you to think about a new constraint: shape instead of size, ranges instead of exact numbers, diagonal separation, or a wrap-around board. Working through them deepens your feel for the original, because you start to see why each of Nurikabe's rules matters by watching what happens when one is changed.

You do not need to master every variant to enjoy Nurikabe, of course. But knowing they exist is a reminder of just how rich this little island puzzle really is. Want to keep your skills sharp on the original first? Play a Nurikabe puzzle now, or revisit the rules before you branch out.

Frequently asked questions

What are the main Nurikabe variants?

The best-known Nurikabe variants include Nuribou (islands become straight strips), Mochikoro and Mochinyoro (the white cells connect instead of the black), pentomino Nurikabe (islands must be five-cell shapes), coded or cipher Nurikabe (numbers replaced by letters), Araf (size ranges instead of exact numbers), No Touch Nurikabe (islands can't touch diagonally either), and toroidal Nurikabe (the grid wraps around).

What is Nuribou?

Nuribou ("paint the stick") is a Nurikabe variant where the white clues form straight strips of a given length instead of islands of a given area. The black region must still stay connected and avoid 2×2 pools, just like classic Nurikabe, so it plays like Nurikabe with straight-line islands.

What is the difference between Nurikabe and Mochikoro?

In classic Nurikabe the black "sea" must be connected and the islands are white. Mochikoro flips this: the white cells must form the connected region, and it is the white areas that avoid 2×2 blocks. Mochikoro is essentially a photo-negative variant of Nurikabe.

Are Nurikabe variants harder than the original?

Some are, some are not, but they are all different. Variants like coded Nurikabe and Araf add a layer (deducing hidden or ranged clue values) that can make them tougher, while toroidal Nurikabe makes connectivity reasoning harder by wrapping the grid. Others simply swap one rule for another without raising the overall difficulty.