Logic Masters Deutschland e.V.

Rules:

Normal Sudoku: Fill the grid with digits 1–9 such that every row, column, and 3 by 3 box contains each digit exactly once.

The Tenth Box: The nine center cells of the standard 3 by 3 boxes form a "Tenth Box" which must also contain the digits 1–9 without repetition.

Any rule or constraint in a standard 3 by 3 box is applied to the corresponding cells in the Tenth Box. Constraints map from the nine standard boxes to the Tenth Box, but not vice-versa.

Killer Cages: Digits in a cage must sum to the value in the top-left corner. Digits cannot repeat within a cage.

Quads: The two digits in the Quad must appear in the surrounding four cells.

Black Dot: If two adjacent cells are separated by a black dot, one number must be exactly double the other.

​Example: In this puzzle, the seventh and eighth cells in Box 1 are inside the cage of sum 10. This means that the sum of the digits in cells R3C1 and R3C2 is 10. Furthermore, the sum of the digits in the seventh and eighth cells of the Tenth Box (R8C2 and R8C5) is also 10.

Example: In this puzzle, the fifth, sixth, eighth and ninth cells in Box 1 surrounds a Quad with digits 2 and 3. This means that both the digits 2 and 3 must appear in R2C2, R2C3, R3C2 and R3C3. Furthermore, the digits 2 and 3 must also appear in the fifth, sixth, eighth and ninth cells of the Tenth Box (R5C5, R5C8, R8C5 and R8C8).

Example: In this puzzle, a black dot sits between the fifth and eighth cells of Box 9. This means that one of the digits in R8C8 and R9C8 is exactly double the other. Furthermore, this constraint maps to the fifth and eighth cells of the Tenth Box, meaning one of the digits in R5C5 and R8C5 must also be exactly double the other.

Solve on Sudokupad

Tenth Box Puzzles:

• 1. The Tenth Box: Unboxing
• 2. The Tenth Box: German Whispers
• 3. The Tenth Box: Renban
• 4. The Tenth Box: Kropki
• 5. The Tenth Box: Dutch Whispers
• 6. The Tenth Box: Killer Cages
• 7. The Tenth Box: Arrows
• 8. The Tenth Box: Quads