GridMew1Check region A
region A has only one remaining candidate: row 1, column 5. Every other cell is excluded by earlier placements or deductions. Place the cat here.
Before step 1. Place one cat, then exclude 9 other cells.Two small top regions simplify a crowded grid
Original puzzle gm-8-0010
By GridMew · Published 15 October 2026 · Updated 16 October 2026
8 × 8 intro
Read the starting position, follow the deductions, and check the move that is easy to misread.
Puzzle board · starting state
How to approach this board
Coordinates such as r2c3 mean row 2, column 3. Count rows from the top and columns from the left.
The three lower givens leave A with r1c5. Its placement then reduces B to r2c7. These two regional singles cut down the larger C and E areas without any candidate lock.
8×8 · 3 fixed cats · 5 explained deductions. Region sizes: A: 3 · B: 5 · C: 16 · D: 7 · E: 8 · F: 7 · G: 11 · H: 7.
A deduction worth checking
Row 5 resolves at r5c6, removing r4c6. That helps the remaining C region settle before the final row-4 placement.
A move to double-check · r3c6
r3c6 touches r2c7 at a corner. Its broad C region does not protect it from the newer B cat’s local neighborhood.
Green marks the cell being discussed, not a cat to place. This is the position before step 2; compare the deduction below.
Read the starting board as text
Each line is one row, left to right. Matching letters belong to the same connected region.
C C C A A B B B C C C A C C B B D C C C C C C C D D D C E E E E D D G G E E E E D F G G G H H H F F F G G G H H F F F G G G H H
Fixed cats: row 8, column 8; row 6, column 2; row 7, column 4. One cat is required in each row, column and region.
Step-by-step walkthrough
2Check region B
region B has only one remaining candidate: row 2, column 7. Every other cell is excluded by earlier placements or deductions. Place the cat here.
Before step 2. Place one cat, then exclude 6 other cells.3Check row 5
row 5 has only one remaining candidate: row 5, column 6. Every other cell is excluded by earlier placements or deductions. Place the cat here.
Before step 3. Place one cat, then exclude 1 other cells.4Check region C
region C has only one remaining candidate: row 3, column 3. Every other cell is excluded by earlier placements or deductions. Place the cat here.
Before step 4. Place one cat, then exclude 2 other cells.5Check row 4
row 4 has only one remaining candidate: row 4, column 1. Every other cell is excluded by earlier placements or deductions. Place the cat here.
Before step 5. Place one cat, then exclude 0 other cells.Show solution · reveals all cat positions
The final cats satisfy every row, column and region quota, with no edge or corner contact.
Cat positions: r1c5, r2c7, r3c3, r4c1, r5c6, r6c2, r7c4, r8c8.
Try another puzzle
Read the lower singles before returning to the top
gm-8-0006 · 8×8 · intro
Practice single-candidate placements on another 8×8 board.
Read this walkthrough →Use the three completed upper rows as constraints
gm-6-0004 · 6×6 · intro
Transfer single-candidate placements to a 6×6 grid; compare how the candidates change.
Read this walkthrough →Let a lower row reserve the right-hand region
gm-8-0002 · 8×8 · challenge
Compare this route with candidate locks, and check why that different rule is needed.
Read this walkthrough →