by Paul Marx, 14 Dec 2025
Please use this page on a computer, as it isn’t made for mobile devices. The following Sudoku combines music with a few special rules:
Normal Sudoku rules apply:
In every row, every column, and every 3×3 box, the digits 1–9 appear exactly once.
2x2 gift boxes:
In Santa’s sack you’ll find five colorful gifts (each a 2×2 set of cells). In each gift box, both diagonals add up to the same sum, and that sum is at least 7. Each gift box has a different diagonal sum.
Choose the difficulty level of the Sudoku by revealing the diagonal sum of one or two gift boxes:
O Thou Joyful:
Play the first four bars of the German Christmas carol “O thou joyful” on the keyboard. The numbers 1–9 are mapped to the notes from C (1) up to D’ (9). This creates a sequence of 20 digits, which appears in exactly this order along the outline of the sack (the light red fields). The direction needs to be deduced by the solver.
Hint:
Here you can find the required passage of the song:
How to use this sudoku app:
With the “Corner” notation, you can place digits in the upper right corner of a cell, and simultaneously use “Center” to put digits in the center of the cell. Use the “Digit” notation to enter the correct digits in large format into the marked cells. Click “Check” to verify your fully solved Sudoku. Click on cells to select them. Hold Shift to select multiple cells. Use the arrow keys to move between cells. Use the 1–9 keys next to the Sudoku or on your keyboard to input digits.
MeinHomestudio.de wishes you lots of fun puzzling and a wonderful, peaceful Christmas season!
Please use this page on a computer, as it isn’t made for mobile devices.