How to Solve Meowdoku
A cat logic puzzle looks like a coloring book and behaves like a proof. This guide covers what the puzzle is, the five tactics that solve real boards, and one 5×5 board taken from an empty grid to a finished solution with the reason for every move.
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What a cat logic puzzle is
A cat logic puzzle is a grid split into colored regions, where you place one cat in every row, every column and every region, and no two cats may sit in touching cells — diagonals included. There are no numbers and nothing to add up. The only thing you ever do is work out where a cat cannot be until one cell is left standing.
Meowdoku is the version this site is about. The same ruleset has been published on paper for years under other names, and the artwork is the only thing that changes: swap the cats for stars and the deductions are identical.
The three rules, in full
- One cat per region. Every colored region holds exactly one cat, whatever shape the region happens to be.
- One cat per row and per column. On a 5×5 board that is five cats in total, one in each line both ways.
- No two cats may touch. Not side by side, not above and below, and not diagonally. Each cat clears the eight cells around it.
A well-formed board has exactly one solution and never requires a guess. Meowdoku's generator enforces that directly: it re-cuts the region borders until only one arrangement of cats survives, and a board that keeps two is thrown away rather than shipped. So if two placements both look legal to you, one of them is not — you have an elimination left to find, not a coin to flip.
The habit that does most of the work
Beginners place cats. Fast solvers mark the cells where a cat cannot go, and let the placements fall out on their own. Every ✕ is permanent information that narrows the board; every cat placed on a hunch is a move you may have to take back, along with everything you built on top of it.
The reason is bookkeeping, not cleverness. One cat removes the rest of its row, the rest of its column, the rest of its region and all eight of its neighbors from play at once. If you do not write those exclusions down, the cell that has just become forced still looks like one candidate among four, and you will scan straight past it.
Five tactics that solve real boards
1. Open with the smallest region
Constraint is information. A region of three cells offers three places to put its cat; a region of eight offers eight. The small ones are where a forced move is most likely to already exist, so they are where you should look first, before you have touched anything else.
This also tells you which board you are on. If the tightest region has five or six cells and nothing is forced from the start, the opening move will come from a row or column instead, and you should start counting lines rather than shapes.
2. A region trapped in one line owns that line
If every cell of a region sits in the same row, that region's cat has to be in that row. The row only ever holds one cat, so every other cell in the row is dead and can be crossed out immediately. The same argument works for a region confined to a single column.
It runs in the other direction too, and that version is easier to miss: when the surviving candidates of a row all happen to lie inside one region, that region's cat is spoken for by the row, and the region's cells outside the row can be crossed out.
3. Draw the whole shadow before looking for the next move
A placed cat kills the rest of its row, the rest of its column, the rest of its region, and all eight cells around it — diagonals included. Mark every one of those before you go hunting again.
Most stalls are not hard positions. They are ordinary positions where part of a shadow was never drawn, so the cell that should have been the obvious next placement still looks like one candidate among several.
4. Count what is left, not what is possible
Rows, columns and regions are the same kind of container: each holds exactly one cat, no more and no less. So the useful question is never "where could a cat go" — it is "which container is down to one live cell".
Scan for containers with two or three candidates remaining. Those are where the next forced move will appear, and there are rarely more than a handful of them on a board at any moment.
5. A cell that touches every candidate is already dead
Suppose a region is down to two candidate cells, and some third cell sits next to both of them. That third cell can be crossed out on the spot: wherever the region's cat lands, this one ends up adjacent to it, and adjacent cats are illegal.
This is the tactic that breaks open boards where nothing else looks forced. It costs a few seconds to check and only ever applies to containers that are already down to two or three candidates, so it is cheap to make a habit of.
One board, worked from start to finish
Here is a 5×5 board with five regions, labelled A to E. It has exactly one solution. Nothing below is a guess: every step names the row, column or region that forces it, and you can check each one against the diagram before reading on.
| 1 | 2 | 3 | 4 | 5 | |
|---|---|---|---|---|---|
| 1 | A | A | A | A | B |
| 2 | C | A | A | B | B |
| 3 | C | C | C | B | B |
| 4 | D | C | C | C | B |
| 5 | D | D | E | E | E |
- Region A — 6 cells: r1c1, r1c2, r1c3, r1c4, r2c2, r2c3
- Region B — 6 cells: r1c5, r2c4, r2c5, r3c4, r3c5, r4c5
- Region C — 7 cells: r2c1, r3c1, r3c2, r3c3, r4c2, r4c3, r4c4
- Region D — 3 cells: r4c1, r5c1, r5c2
- Region E — 3 cells: r5c3, r5c4, r5c5
- Region E is three cells wide and all three of them — r5c3, r5c4 and r5c5 — sit in row 5. Row 5 gets exactly one cat, and it has to be one of those three, so cross out the rest of row 5: r5c1 and r5c2. No cat has been placed yet and the board has already lost two cells.
- Look at region D: r4c1, r5c1 and r5c2. Two of them were just crossed out. One live cell remains, so the first cat goes at r4c1.
- Draw the shadow. Column 1 and row 4 are finished, and r3c1 and r3c2 are neighbors of the new cat. Region C started with seven cells; six of them are now dead, and the survivor is r3c3. Second cat.
- Shadow again: row 3 and column 3 are done, and r2c2, r2c3 and r2c4 are neighbors. Row 2 had already lost r2c1 to column 1, which leaves r2c5 as its only live cell. Third cat.
- Column 5 clears r1c5, r3c5, r4c5 and r5c5, and the neighbors of the new cat take r1c4 and r3c4. Row 5 lost c1 and c2 in step one and c3 to column 3, so only r5c4 is left. Fourth cat, and region E is satisfied exactly where step one predicted.
- Row 1 has lost c1 to column 1, c3 to column 3, c4 to the cat at r2c5, and c5 to column 5. The last cat goes at r1c2, and every row, column and region now holds exactly one.
| 1 | 2 | 3 | 4 | 5 | |
|---|---|---|---|---|---|
| 1 | A | 🐱 | A | A | B |
| 2 | C | A | A | B | 🐱 |
| 3 | C | C | 🐱 | B | B |
| 4 | 🐱 | C | C | C | B |
| 5 | D | D | E | 🐱 | E |
Six steps, five cats, no guesses. The opening move placed nothing at all — it only crossed out two cells — and that is what made the whole chain possible. Boards that feel impossible are usually boards where the first elimination has not been found yet.
Mistakes that stall beginners
- Placing a cat because it looks right
- A placement you cannot justify is a guess, and a guess on a single-solution board is a move you will eventually have to unwind. If you cannot name the row, column or region that forced it, mark ✕ somewhere else instead and come back.
- Forgetting that diagonals count
- The no-touching rule covers all eight neighbors. Diagonal contact is the most common illegal placement by a wide margin, because a diagonal pair breaks no row and no column and therefore looks fine at a glance.
- Treating a region like a row
- Regions bend. One can span four rows and two columns, or sit as a 2×2 block in a corner. Its cat is constrained by its shape, not by any line, which is exactly why the lockout tactic above is worth checking on every region.
- Erasing ✕ marks to "clean up"
- Those marks are the solution in progress. A board that looks messy is a board that is nearly solved; a board that looks clean halfway through is one you are solving from memory.
- Restarting instead of finding the contradiction
- When a board becomes unsolvable, an earlier placement was wrong, and it is usually the last one you could not justify. Working backwards from the container that ran out of cells finds it faster than starting over.
How difficulty scales with board size
A 4×4 board is mostly the no-touching rule: with four cats on sixteen cells there is barely room to go wrong, and the regions rarely need thinking about. A 5×5 board like the one above is where the region tactics start to matter, which is why it is the right size to learn on.
From 7×7 upward the change is quantitative rather than conceptual. The rules are the same, but you are tracking twenty-one containers instead of fifteen, and no single one of them stays in your head. That is where the line-lockout and touching-cell tactics earn their keep: they produce eliminations without requiring you to hold the whole board in view at once.
Board sizes in the free browser version scale with your screen, so you can move up a size whenever the current one stops resisting.
Questions people ask
Is a cat logic puzzle the same thing as sudoku?
No. Both ask for one of something per row and column, but sudoku fills every cell with a digit, and a cat logic puzzle places a single cat per row, column and region on a mostly empty grid. The no-touching rule has no sudoku equivalent at all, and it is what most of the deduction actually turns on.
Do cat logic puzzles ever require guessing?
A well-formed board never does. It has exactly one solution, and that solution is reachable by elimination alone. If you are stuck choosing between two placements that both look legal, there is an elimination you have not spotted yet — most often a region locked into one line, or a cell that touches every remaining candidate of some container.
What board size should a beginner start on?
A 5×5 board, like the one worked through above. It is small enough that the whole grid stays in view and large enough that the region shapes matter. Boards of 4×4 rarely need more than the no-touching rule, and 8×8 and up ask you to track sixteen containers at once, which is a different kind of work.
How do I check a board I am stuck on?
The Meowdoku solver takes a screenshot of a board and returns the solved position. Detection and solving both run inside your browser, so the image is never uploaded anywhere. It is more useful as a check on your own reasoning than as a shortcut.
Where can I play a cat logic puzzle for free?
On the home page of this site, with no download and no account — board sizes scale to your screen, and there is a daily puzzle and a campaign. The original mobile game is also free on both stores; the download page has the official links.
Where to go next
Corrections and questions are welcome at the contact page.