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 12 other cells.A singleton turns a large board into a sequence of singles
Original puzzle gm-8-0003
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 board is 8×8, but its route begins simply: A is the single cell r1c5. Combined with the two givens, its row and neighborhood effects reduce B to r2c3.
8×8 · 2 fixed cats · 6 explained deductions. Region sizes: A: 1 · B: 2 · C: 9 · D: 9 · E: 22 · F: 11 · G: 7 · H: 3.
A deduction worth checking
After B is filled, D resolves at r4c8. That cat clears the rest of row 4 and column 8, allowing the bottom-right H placement.
A move to double-check · r5c7
r5c7 is a corner neighbor of r4c8. Large regions can distract from a local exclusion that is just as decisive on a small board.
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.
C C B E A D D D C C B E E D D D C C C E E E D D C F C E E E E D F F F E E E E E F F F G E E E E F F G G G E E H F F G G G E H H
Fixed cats: row 6, column 2; row 3, column 1. 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 3. Every other cell is excluded by earlier placements or deductions. Place the cat here.
Before step 2. Place one cat, then exclude 3 other cells.3Check region D
region D has only one remaining candidate: row 4, column 8. Every other cell is excluded by earlier placements or deductions. Place the cat here.
Before step 3. Place one cat, then exclude 7 other cells.4Check region H
region H 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 4. Place one cat, then exclude 4 other cells.5Check row 7
row 7 has only one remaining candidate: row 7, column 4. Every other cell is excluded by earlier placements or deductions. Place the cat here.
Before step 5. Place one cat, then exclude 1 other cells.6Check 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 6. 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, r2c3, r3c1, r4c8, r5c6, r6c2, r7c4, r8c7.
Try another puzzle
A one-cell region sends information across the board
gm-8-0007 · 8×8 · intro
Practice single-candidate placements on another 8×8 board.
Read this walkthrough →Resolve the outside rows before the top centre
gm-5-0010 · 5×5 · intro
Transfer single-candidate placements to a 5×5 grid; compare how the candidates change.
Read this walkthrough →A shared neighborhood settles the right edge
gm-6-0007 · 6×6 · challenge
Compare this route with shared-neighbor exclusions, and check why that different rule is needed.
Read this walkthrough →