GridMew1Check row 6
row 6 has only one remaining candidate: row 6, column 6. Every other cell is excluded by earlier placements or deductions. Place the cat here.
Before step 1. Place one cat, then exclude 1 other cells.Read the lower singles before returning to the top
Original puzzle gm-8-0006
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 givens occupy rows 1, 5 and 7. Begin with row 6, where their combined constraints leave r6c6. The next useful single is in row 8, not necessarily beside the newest cat.
8×8 · 3 fixed cats · 5 explained deductions. Region sizes: A: 2 · B: 13 · C: 8 · D: 3 · E: 12 · F: 5 · G: 18 · H: 3.
A deduction worth checking
Once r8c7 is placed, row 2 resolves at r2c5. Its effects remove r3c5 and r4c5, allowing the remaining central rows to settle.
A move to double-check · r4c5
r4c5 does not touch r2c5. They share column 5, so the new cat still excludes it.
Green marks the cell being discussed, not a cat to place. This is the position before step 3; 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.
A A C B B B B B C C C B B B B B C C C B B E B E G C D D D E E E G G G E E E E E G G G G E F F E G G G G F F F H G G G G G G H H
Fixed cats: row 7, column 4; row 1, column 2; row 5, column 8. One cat is required in each row, column and region.
Step-by-step walkthrough
2Check row 8
row 8 has only one remaining candidate: row 8, column 7. Every other cell is excluded by earlier placements or deductions. Place the cat here.
Before step 2. Place one cat, then exclude 2 other cells.3Check row 2
row 2 has only one remaining candidate: row 2, column 5. Every other cell is excluded by earlier placements or deductions. Place the cat here.
Before step 3. Place one cat, then exclude 2 other cells.4Check row 4
row 4 has only one remaining candidate: row 4, column 3. Every other cell is excluded by earlier placements or deductions. Place the cat here.
Before step 4. Place one cat, then exclude 1 other cells.5Check row 3
row 3 has only one remaining candidate: row 3, 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: r1c2, r2c5, r3c1, r4c3, r5c8, r6c6, r7c4, r8c7.
Try another puzzle
Two small top regions simplify a crowded grid
gm-8-0010 · 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 →