GridMew1Check region C
region C has only one remaining candidate: row 3, column 2. Every other cell is excluded by earlier placements or deductions. Place the cat here.
Before step 1. Place one cat, then exclude 8 other cells.The central singleton releases a lower-right region
Original puzzle gm-6-0057
By GridMew · Published 15 October 2026 · Updated 16 October 2026
6 × 6 practice
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.
Region C at r3c2 supplies the first cat. The fixed r4c5 cat has already filled D; together their effects narrow F to a bottom-right position.
6×6 · 1 fixed cats · 5 explained deductions. Region sizes: A: 7 · B: 8 · C: 1 · D: 5 · E: 9 · F: 6.
A deduction worth checking
F resolves at r6c6. With that lower row and column occupied, row 2 can use r2c4, whose next effects reach the top row.
A move to double-check · r2c3
r2c3 touches the first cat at r3c2. Crossing it out depends on the actual corner contact, not on region C extending into row 2.
Green marks the cell being discussed, not a cat to place. This is the position before step 1; 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 B B B B A A B B B B A C E D D D A E E D D F A E E F F F E E E E F F
Fixed cats: row 4, column 5. One cat is required in each row, column and region.
Step-by-step walkthrough
2Check region F
region F 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 2. Place one cat, then exclude 5 other cells.3Check row 2
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 3. Place one cat, then exclude 2 other cells.4Check row 1
row 1 has only one remaining candidate: row 1, 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.5Check row 5
row 5 has only one remaining candidate: row 5, column 3. 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: r1c1, r2c4, r3c2, r4c5, r5c3, r6c6.
Try another puzzle
A bottom-left singleton opens a distant column
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Practice single-candidate placements on another 6×6 board.
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gm-5-0029 · 5×5 · practice
Transfer single-candidate placements to a 5×5 grid; compare how the candidates change.
Read this walkthrough →Two possible cats, one shared exclusion
gm-5-0001 · 5×5 · challenge
Compare this route with shared-neighbor exclusions, and check why that different rule is needed.
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