Meowdoku Tips & Tricks

Find a certain move, carry its consequences across the board, and use the remaining candidates to find the next one. These six worked examples show how to get past a guess.

The rules behind every deduction

One cat in each row.
One cat in each column.
One cat in each color region.
Cats cannot touch, even at a corner.

R counts rows from the top; C counts columns from the left. R1C2 is the top row's second square. Letters A–F identify color regions.

Original teaching boards, not numbered Meowdoku levels. Some examples intentionally allow several solutions: each deduction shown still holds in every solution.

01 / 06

Start with the only candidate

Count the places a cat can still go, not just the squares in a small region.

Teaching board · 4 × 4

Candidate under discussion

The ring marks the only cell in B. It is a logical placement, not a guess.

When it applies

A row, column, or color region still needs its cat and has exactly one legal cell left. Every other cell must have a reason for being excluded.

Work through the example

Region B contains just R1C2. It needs one cat, so R1C2 is forced even before any other cat is placed.
Region C has three cells: R3C1, R3C2, and R4C1. Being small does not tell you which of those three is correct yet.
Place the forced cat at R1C2, then check its row, column, region, and neighboring squares before looking for the next single.

Why it works

Exactly one cat must occupy region B. With only one available cell, every complete solution must use R1C2. The same argument works for a row or column after valid exclusions reduce it to one candidate.

Watch out

Do not choose a square merely because its region is small. Two candidates mean there is still a choice. Zero candidates mean an earlier placement, exclusion, or board reading needs checking.

02 / 06

Let one cat rule out four kinds of cells

A confirmed placement gives you a whole set of useful exclusions.

Teaching board · 6 × 6

Ruled out
Confirmed cat: R2C4

R2C4 is confirmed. Every X follows directly from that one placement; unmarked cells remain undecided.

When it applies

The cat at R2C4 is confirmed. If it was only a trial placement, the exclusions are conditional too.

Work through the example

Clear the rest of row 2 and column 4. For example, R2C1 and R6C4 can no longer contain a cat.
Clear every other B cell, including R1C6. It shares the cat's region even though it is neither in the same row nor the same column.
Clear the diagonally touching cells too. R3C3 and R3C5 are excluded by contact; now recount candidates in the affected regions.

Why it works

The row, column, and region each already have their one cat. An edge or corner neighbor would touch it. Apply all four checks together; each X in this diagram follows directly from the confirmed cat.

Watch out

Do not stop at the nearby squares: the row and column extend across the entire board. Do not treat the unmarked cells as confirmed cats either; they still have to satisfy the remaining constraints.

03 / 06

Catch a diagonal conflict before it spreads

Different rows, columns, and colors are necessary, but not sufficient.

Teaching board · 6 × 6

Confirmed cat: R2C4
Invalid trial cat: R3C5

The red-crossed cat at R3C5 is an intentionally invalid trial. It touches R2C4 at a corner.

When it applies

You are checking a proposed cat near a confirmed one. Look at corner contact as well as shared edges.

Work through the example

Keep the confirmed B cat at R2C4. The crossed-out trial is R3C5 in region C.
The two positions pass the row, column, and region tests: rows 2 and 3, columns 4 and 5, regions B and C are all different.
They still share a corner. Remove the trial at R3C5; it is not a legal second cat.

Why it works

For touching squares, the row difference and column difference are both at most one. Here each difference is exactly one, so this is diagonal contact. All eight neighboring squares are forbidden around a cat.

Watch out

This is not Sudoku's fixed 3×3-box rule, and cats do not attack along an entire diagonal like chess queens. A distant square is not excluded just because it lies on the same diagonal.

04 / 06

Reserve a row for a color region

Sometimes you know the cat's row before you know its square.

Teaching board · 6 × 6

Candidate under discussion
Ruled out

Both circled B cells are in row 1. The X cells are excluded without choosing either B candidate.

When it applies

Every remaining candidate of one unsolved region lies in the same row. The column version uses exactly the same reasoning.

Work through the example

B has just two candidates, R1C2 and R1C3. Both are in row 1.
Whichever B cell wins, row 1 will get its one cat from B. Exclude R1C1, R1C4, R1C5, and R1C6 from the other regions.
Keep both B candidates for now. Move to the affected A and C regions and see whether the exclusions produce a new single or another locked line.

Why it works

The row's cat must be supplied by B, so no other region can use that row. This conclusion is true for both B choices. In this teaching board, each B candidate appears in at least one complete solution.

Watch out

Two B cells in one row are not enough if B has a third legal candidate elsewhere. Check the entire region. Also, reserving a row does not let you pick arbitrarily between the two circled cells.

05 / 06

Use two regions to reserve two columns

Count the cats that must fit into a set of columns, then revisit the remaining regions.

Teaching board · 6 × 6

Candidate under discussion
Ruled out

The rings show all A and B candidates. The four X cells in D are excluded by the two-column reservation.

When it applies

Two distinct unsolved regions have all their candidates within the same two columns. Neither region can use a third column.

Work through the example

A occupies R1C1, R1C2, R2C1, R2C2. B occupies R4C1, R4C2, R5C1, R5C2. Both regions are limited to columns 1 and 2.
A and B each need one cat, and those cats cannot share a column. Together they must use both columns 1 and 2.
Exclude D's R3C1, R3C2, R6C1, and R6C2. D is now confined to column 3, so the locked-line technique also excludes C's R1C3 and R2C3 next.

Why it works

Two required cats occupy two different columns chosen from a set of only two. That leaves no capacity in those columns for any other region. The follow-up deduction links the pair back to a single region and then to another column.

Watch out

Do not require A to use column 1 and B to use column 2; they can swap. If either region has a candidate in column 3, the pair is not established. These deductions do not by themselves solve every remaining cell.

06 / 06

Audit your marks when a board seems impossible

A contradiction is a reason to inspect the input and the last deduction.

Teaching board · 4 × 4

Mistaken X: R1C2

The red X is intentionally wrong. Removing it restores B's only candidate at R1C2.

When it applies

A row, column, or region has no candidates, or the solver reports invalid input or no solution. Review tentative marks before treating them as facts.

Work through the example

The red X at R1C2 is a deliberately mistaken player mark. It removes the only cell in B, leaving that region unable to contain its required cat.
Undo that unsupported X. The original teaching board has one complete solution: R1C2, R2C4, R3C1, R4C3. The mark, rather than the board, caused the contradiction.
For your own screenshot, compare every color region and any detected cats or X marks with the original. Check whether a displayed cat is a given or your own trial, and confirm that a numbered guide matches your board.

Why it works

An X records a deduction; it does not prove the deduction was correct. A screenshot solver can only reason from the board and constraints it receives. Restoring the missing candidate fixes this example, but another board may require undoing a different assumption.

Watch out

Do not erase genuine fixed cats to force a desired answer. Multiple solutions mean the current input allows more than one answer, not that a guessed one is uniquely correct. If search is needed, label it as a trial or search check rather than inventing a logical step.

Questions that come up mid-puzzle

Is Meowdoku the same as Sudoku?: No. These puzzles use one cat per row, column, and color region, plus a no-touching rule. There are no numbers to fill and no fixed Sudoku-style 3×3 boxes.
Does a small region always tell me the next cat?: Only when it has exactly one legal candidate. If two or more remain, look for a locked line, a region pair, or deductions elsewhere before choosing.
Can I use these diagrams as an answer to my level?: These are original teaching boards. Use the level guides or upload your own screenshot for your particular board; the same level number can differ between versions.

Put the reasoning into practice

Try an original browser puzzle, find a numbered level guide, or check your own board with a screenshot.

Play a practice puzzle Find a level guide Solve a screenshot