What is Nanro?
Nanro is a number-labelling logic puzzle played on a grid that has been divided by bold walls into regions. In each region you fill some of the cells with a number and leave the rest blank, and the rule that ties everything together is delightfully self-referential: the number you write equals how many cells in that region are filled. So a region with two filled cells shows a 2 in each, a region with four filled cells shows a 4 in all four, and every region must have at least one filled cell.
Three more rules shape the whole board. All the filled cells across the grid must connect into one single group, joined edge to edge. No 2x2 square may be completely filled. And when two filled cells sit next to each other across a region border, their numbers must be different. Put the self-counting label together with those three constraints and the grid has exactly one way to be filled - a single connected, branching ribbon of numbers threading between the regions.
- Bold walls divide the grid into regions.
- Fill some cells in each region; every region needs at least one.
- A filled cell's number equals how many cells in its region are filled.
- All the filled cells must connect into one single group.
- No 2x2 square may be entirely filled.
- Equal numbers may not touch across a region border.
How to play Nanro online
Click or tap a cell to fill it; click again to clear it. Each filled cell shows a live count of how many cells are currently filled in its region, so the number updates as you work - when a region is right, every filled cell in it matches. The given numbers are printed in a darker, fixed style and are always filled. Right-click a cell to pencil a small cross when you have decided it stays blank; it never changes the puzzle, it just keeps your reasoning on the board.
Check looks over your grid and flags any cell that disagrees with the unique solution, without telling you what it should be. Hint fills one correct cell - or clears a wrong one - Undo steps back, Reset clears the board, and Solution fills the whole grid when you would rather study a finished puzzle than complete it. New puzzle builds a fresh board for the size and difficulty you have chosen.
- Tap a cell to fill it; tap again to clear it.
- Each filled cell shows the live count for its region.
- Given numbers are fixed and always filled.
- Right-click a cell to mark it blank; it is just a note for you.
- Check, Hint, Undo, Reset and Solution help when you get stuck.
The count is the clue
Every given number does double duty: it tells you a cell is filled, and it tells you exactly how many cells in that whole region are filled. A 1 means its region has a single filled cell - the one you can see - so every other cell in that region is blank. A 3 means the region has exactly three filled cells, so once you find the third, the rest are blank. Reading each given as a region total, not just a single mark, is the first habit to build.
Small regions are the friendliest place to start. A two-cell region must hold either a single 1 or a pair of 2s, and a neighbouring number often decides which. A region the same size as its given number is completely filled - if a four-cell region shows a 4, colour all four. And because a region's number can never exceed its size, a large given immediately rules out the small regions around it. Let the givens fix the easy regions first, then use what they imply about their neighbours.
- A given is both a filled cell and its region's total count.
- A 1 fills one cell in its region; the rest of that region is blank.
- A region whose number equals its size is completely filled.
- A number can never be larger than the size of its region.
- Solve the small and fully-determined regions first.
Keep the numbers connected
The connection rule is easy to forget and powerful to use: every filled cell on the whole board must join into one single group, edge to edge. That means the numbers can never split into two separate islands. If filling a cell would strand a group of numbers with no way back to the rest, that fill is wrong - and just as often, a region that would otherwise be cut off forces a particular cell to be filled so the chain can pass through it.
This is where Nanro starts to feel like a path puzzle. A region tucked in a corner has to reach its neighbours somehow, so the filled cells bridging it to the rest of the grid are frequently forced. Look for narrow gaps where the single group of numbers must squeeze through, and for blank cells that would otherwise break the chain. Keeping the whole ribbon connected is as much a solving tool as the counts themselves.
- All filled cells must form one connected group, edge to edge.
- The numbers can never split into two separate islands.
- A fill that would strand a group of numbers is illegal.
- A region must connect to its neighbours, which forces bridge cells.
- Watch the narrow gaps the single group must pass through.
No 2x2, and no equal neighbours
Two more rules keep the numbers from clumping. No 2x2 square anywhere on the grid may be completely filled, which stops the numbers forming solid blobs and quietly forbids the fourth cell whenever three corners of a little square are already filled. It is an easy rule to apply and a constant source of forced blanks, so glance at every 2x2 as you go.
The last rule guards the borders: when two filled cells are next to each other but lie in different regions, their numbers must differ. Since every filled cell in a region carries the same number, this is really a statement about region totals - two regions that touch cannot both place a filled cell against the shared wall if their counts are equal. That often forces where, exactly, a region puts its filled cells, and it can even pin down a region's count by ruling out a value its neighbour has already claimed along the border.
- No 2x2 square may be entirely filled - the fourth cell is forbidden.
- Glance at every 2x2 to catch forced blank cells.
- Filled cells touching across a border must show different numbers.
- Two touching regions cannot meet at the wall with equal counts.
- The border rule can fix where a region places its filled cells.
Where Nanro comes from
Nanro is a modern logic puzzle that grew up in the online puzzle community rather than the classic Japanese magazines, and it spread through puzzle blogs, competitive-solving sites and championship rounds. Its name is usually written in capitals, and a well-known relative called Nanro Signpost adds a small arrow or marker to each region to show where its count goes - a variant that helped the original travel. The base puzzle, with its self-counting regions, has become a staple of pencil-puzzle collections for solvers who like a fresh twist on region logic.
What makes Nanro feel distinctive is how its rules feed on each other. The self-referential count is a tidy idea on its own, but bolting on connectivity, the no-2x2 rule and the border-difference rule turns it into a genuine deduction puzzle that blends counting, shading and path-finding. Few puzzles ask you to balance a region's total against the need to keep a single connected ribbon of numbers alive, which is exactly what gives Nanro its particular, moreish character.
Nanro vs Suguru, Fillomino and Nurikabe
Nanro sits among the region puzzles but mixes their ingredients in a new way. Like Suguru and Fillomino it is built on irregular regions, but where those ask you to place a full set of numbers, Nanro asks you to choose how many cells to fill and then labels them with that count. Where Fillomino's number tells you the size of a same-numbered area, Nanro's number tells you how many cells in a fixed region are filled - a subtle but very different question that pulls in shading and connectivity.
The connection and no-2x2 rules give it a strong family resemblance to shading puzzles like Nurikabe, where you also keep a connected area and avoid solid 2x2 pools. Nanro layers a counting clue on top of that shading skeleton, so solvers who enjoy Nurikabe's connectivity logic or Suguru's region thinking tend to take to it quickly. If you like region puzzles and want something that feels both familiar and genuinely new, Nanro is an easy and rewarding next step.
- Suguru: fill every region with 1 to N; equal numbers may not touch.
- Fillomino: a number is the size of its same-numbered area.
- Nurikabe: keep one connected shaded area and avoid 2x2 pools.
- Nanro: a number is how many cells in its fixed region are filled.
- Nanro blends counting, shading and connected-path logic.
Grid sizes and difficulty levels
The 6x6 boards are the place to learn the rhythm: a handful of small regions, short chains of numbers, and givens that resolve a region in a step or two. On 7x7 there are more regions and the connected ribbon winds further, so the no-2x2 rule and the connection rule start doing real work alongside the counts. The 8x8 boards are full puzzles - many regions, a long connected group of numbers, and deductions that travel right across the grid before a single cell is sure.
Difficulty changes how many numbers are revealed to start. Easy boards show plenty of the region totals, so most cells fall to a short, local deduction and the grid fills steadily. Medium reveals fewer numbers, leaving more regions to be worked out from their neighbours and from the connection rule. Hard shows the least, so you lean hard on connectivity, the no-2x2 rule and the border differences for longer before the grid gives way. Whichever you choose, every board is checked by a solver before you see it and only those with exactly one solution are kept - so each puzzle is always solvable by pure logic, never by guessing.
- 6x6 - small regions and short chains to learn the rules.
- 7x7 - more regions and a longer connected ribbon of numbers.
- 8x8 - many regions and deductions that cross the whole grid.
- Easy, medium and hard change how many numbers are revealed.
- Every puzzle is verified to have exactly one solution.