The fastest way to get better at Nurikabe is to think wall first: wall in complete islands, wall between islands, and wall everything no island can reach. We measured these tips on all 150 of the game’s levels, and the numbers below come from those tests.
These build on how to solve Nurikabe. If you haven’t played before, start with the rules.
Solving tips
1. Start with the 1s
A 1 is a complete island, so every square beside it is wall. A 1 is the first move on 35 of the 50 Easy levels, 36 Medium and 43 Hard.
2. Wall between numbers
A square touching two numbers, or two islands, would join them. It’s wall. On levels without a 1, that’s almost always the first move.
3. Think wall first
Most of the grid is wall. Of all the squares the hints settle, 81% are wall on Easy, 78% on Medium and 77% on Hard. When you’re not sure what to look for, look for wall.
4. Close in every complete island
As soon as an island has all its squares, wall it in. Complete islands and squares between islands give 52% of all the wall on Easy, 53% on Medium and 56% on Hard.
5. Ask how far each island can reach
An island can only grow as far as its number allows. A square that no island can reach is wall, and that’s 44% of the wall on Easy, 38% on Medium and 35% on Hard. Count outwards from each number: a 2 reaches only its neighbours, a 3 reaches two steps.
6. Watch for 2×2 blocks
Wherever three walls meet in a 2×2 block, the fourth square is island. It’s needed on 49 of the 50 Easy levels and all of the others, 3.8 times per Easy level on average, 7.4 on Medium and 12.1 on Hard.
Tips for playing on PeerPuzzles
7. Tap to cycle, right-click to go back
Tap a square once for wall, again for a dot (island), and again to clear it. Numbered squares are island from the start. On a computer, right-click cycles the other way, Ctrl/Cmd + Z undoes a move, and H asks for a hint.
8. Let the marks and Stuck? help
A 2×2 block of wall gets a red outline, an island that can’t be right turns its number red, and a finished wall in pieces gets a red frame. If you’re stuck, Stuck? highlights the squares to look at and names the technique, without filling anything in for you. If one of your squares is wrong, it rings that square first.