Insula · Free in your browser
Insula: Nurikabe Puzzle
Form islands in the sea. Pure logic deduction — never guessing.
The rules
- Land
- Sea
- Split the grid into land and sea.
- Every number belongs to an island of exactly that many cells.
- Every island contains exactly one number.
- Islands never touch left, right, up or down. Corners are fine.
- All the sea is one connected body.
- The sea never fills a whole 2x2 block.
- Only two mistakes are pointed out as you play: an island with too many cells, and a 2x2 block of sea. A too-small island or a sea cut into two pieces won't be marked — so a full board with no warnings on it can still be wrong.
- Tap a cell to mark it sea, tap again to clear it. Long-press to mark it land. Drag to mark a run.
- Every puzzle here is solvable by reasoning alone. You never have to guess.
- Got it
How to play here
Three ways to play
Campaign
Chapters that start gently and bring in one new idea at a time.
Daily puzzle
A new board every day, the same for everyone. Solve every one in a month and that month's trophy is yours.
Endless
Keep going as long as you like, in Easy, Medium, Hard and Expert.
About the game
Insula is a Nurikabe puzzle — also known as Islands in the Stream — for players who like unhurried, honest logic.
Every number marks an island of exactly that many cells. Every island holds exactly one number, and islands never touch horizontally or vertically. Everything else is sea: one connected ocean that nowhere forms a solid 2x2 block of water.
Never a guess
Every puzzle has exactly one solution, and every step of it can be reasoned out. Each board is verified by a solver that only uses techniques a person can follow and explain — so a puzzle that would need trial and error never ships. The hint button uses that same solver, which means a hint is always a move you could have found yourself, and it tells you which idea it used.
Learn it by playing it
Nurikabe does not explain itself the way most grid puzzles do: two of its rules are about the board as a whole. The walkthrough hands you real positions and asks for the one square that follows, then shows you why. No board in it was made up — each is a genuine puzzle stopped at the moment the idea it teaches becomes the forced next move.
All offline, no account
- 12 campaign chapters, 360 levels, from gentle openings to genuine work
- A daily puzzle, the same one for every player worldwide, with a gentle Monday and a demanding Sunday
- Endless mode in four difficulties: Easy, Medium, Hard, Expert
Measured in months, not streaks
Fill in every day of a calendar month and the month earns its own trophy. There is no streak to lose: a day you missed can still be filled in from the archive, so a week away from the game costs you nothing.
Built to be pleasant
- Warm Material 3 design, light and dark, following your system colours
- Completely offline — no account, no sign-in, no network needed
- Boards shaped for a phone held in one hand
- No countdowns you did not ask for and no interruptions
27 languages supported. No account required. Pure logic.
Common questions
Is Insula free?
Yes. You can play here without paying and without an account. Ads keep the lights on.
Where is my progress saved?
In this browser, on this device. If you clear the site data, your progress goes with it. A free Solvarium account keeps it safe.
Does it work on a phone or tablet?
Yes. It runs in any current browser on phones, tablets and computers, and the board resizes to fit the screen.
Does every puzzle really have one solution?
Yes. Every board goes through a solver before it ships, and anything with more than one solution is thrown out.