Original puzzle gm-6-0015
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 givens fill B and E. Row 1 is confined to A at columns 4–6. That gives a reservation, not a placement; use it to remove A’s protruding lower cell.
6×6 · 2 fixed cats · 5 explained deductions. Region sizes: A: 7 · B: 8 · C: 2 · D: 7 · E: 9 · F: 3.
r3c4 belongs to A but is outside row 1. Once excluded, row 3 forces r3c6, and the remainder proceeds through singles.
There is no requirement to guess a top-row column. Any valid top-row cat must also be A’s only cat, so r3c4 cannot hold another.
Green marks the cell being discussed, not a cat to place. This is the position before step 1; compare the deduction below.
Each line is one row, left to right. Matching letters belong to the same connected region.
B B B A A A B B B A A A D B B A E C D D E E E C D D E E E F D D E E F F
Fixed cats: row 5, column 3; row 2, column 2. One cat is required in each row, column and region.
Every candidate in row 1 lies in region A (row 1, column 4; row 1, column 5; row 1, column 6). Its cat must use that shared section. Exclude row 3, column 4 from the rest of region A.
Before step 1. Exclude 1 cells; then scan for a new single.row 3 has only one remaining candidate: row 3, column 6. 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.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 3. Place one cat, then exclude 1 other cells.row 6 has only one remaining candidate: row 6, column 5. 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.row 1 has only one remaining candidate: row 1, column 4. 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.The final cats satisfy every row, column and region quota, with no edge or corner contact.
Cat positions: r1c4, r2c2, r3c6, r4c1, r5c3, r6c5.
gm-6-0019 · 6×6 · challenge
Practice candidate locks on another 6×6 board.
Read this walkthrough →gm-8-0002 · 8×8 · challenge
Transfer candidate locks to a 8×8 grid; compare how the candidates change.
Read this walkthrough →gm-6-0007 · 6×6 · challenge
Compare this route with shared-neighbor exclusions, and check why that different rule is needed.
Read this walkthrough →
GridMew