Original puzzle gm-6-0002
By GridMew · Published 15 October 2026 · Updated 16 October 2026
6 × 6 challenge
Read the starting position, follow the deductions, and check the move that is easy to misread.
Coordinates such as r2c3 mean row 2, column 3. Count rows from the top and columns from the left.
The top-right given occupies A. Row 2 is confined to B, and that reservation strips B’s candidates from row 3. Keep both row-3 possibilities until their shared effect has been used.
6×6 · 1 fixed cats · 8 explained deductions. Region sizes: A: 2 · B: 13 · C: 7 · D: 2 · E: 10 · F: 2.
Row 3’s r3c1 and r3c2 are both in C. Reserving C for that row removes its lower cells; the next neighbor exclusion then forces column 1.
Both remaining row-3 candidates touch r2c2. The exclusion is valid before knowing which one will be chosen, so guessing between them would skip the useful deduction.
Green marks the cell being discussed, not a cat to place. This is the position before step 3; compare the deduction below.
Each line is one row, left to right. Matching letters belong to the same connected region.
B B B B B A B B B B B A C C B B B E C C D E E E C C D E E E C F F E E E
Fixed cats: row 1, column 6. One cat is required in each row, column and region.
Every candidate in row 2 lies in region B (row 2, column 1; row 2, column 2; row 2, column 3; row 2, column 4). Its cat must use that shared section. Exclude row 3, column 3; row 3, column 4; row 3, column 5 from the rest of region B.
Before step 1. Exclude 3 cells; then scan for a new single.Every candidate in row 3 lies in region C (row 3, column 1; row 3, column 2). Its cat must use that shared section. Exclude row 4, column 1; row 4, column 2; row 5, column 1; row 5, column 2; row 6, column 1 from the rest of region C.
Before step 2. Exclude 5 cells; then scan for a new single.The cat in row 3 must occupy one of row 3, column 1; row 3, column 2. Each of row 2, column 1; row 2, column 2 touches every candidate, so none can hold a cat.
Before step 3. Exclude 2 cells; then scan for a new single.column 1 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 4. Place one cat, then exclude 1 other cells.column 2 has only one remaining candidate: row 6, column 2. Every other cell is excluded by earlier placements or deductions. Place the cat here.
Before step 5. Place one cat, then exclude 4 other cells.region D 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 6. Place one cat, then exclude 4 other cells.row 2 has only one remaining candidate: row 2, column 4. Every other cell is excluded by earlier placements or deductions. Place the cat here.
Before step 7. Place one cat, then exclude 0 other cells.row 5 has only one remaining candidate: row 5, column 5. Every other cell is excluded by earlier placements or deductions. Place the cat here.
Before step 8. Place one cat, then exclude 0 other cells.The final cats satisfy every row, column and region quota, with no edge or corner contact.
Cat positions: r1c6, r2c4, r3c1, r4c3, r5c5, r6c2.
gm-6-0012 · 6×6 · challenge
Practice candidate locks on another 6×6 board.
Read this walkthrough →gm-5-0012 · 5×5 · challenge
Transfer candidate locks to a 5×5 grid; compare how the candidates change.
Read this walkthrough →gm-8-0053 · 8×8 · practice
Compare this route with single-candidate placements, and check why that different rule is needed.
Read this walkthrough →
GridMew