Logic Masters Deutschland e.V.

Collaboration with filuta. If you have not solved filuta’s puzzles, I highly recommend that you do! Especially this one (which was just featured on CTC!)

This collab started with filuta’s idea of a snake that travels outside the grid, and resulted in a puzzle that we think is pretty neat :) Many thanks to Piatato and henrypijames for testing. Difficulty estimated at 3½ stars. Enjoy!

Rules:

11x11 grid with 9x9 Sudoku: This puzzle is an 11x11 grid with a normal 9x9 Sudoku centered inside. Within the 9x9 Sudoku grid, normal Sudoku rules apply: place the digits 1 to 9 in every row, column, and 3x3 box.

Oddly Unconstrained Snake:

• Draw a snake (non-looping, non-branching 1-cell wide path of orthogonally connected cells) that may touch itself diagonally. The two ends of the snake are given as large white circles.
• Within the 9x9 Sudoku, all of the odd digits (and none of the even digits) belong to the snake.
• The snake may appear in any cell within the 11x11 grid, and may move in and out of the 9x9 Sudoku as necessary. Cells outside the 9x9 Sudoku have no numerical value—they exist only for the snake.

Standard Kropki—No Negative Constraint:

• Digits separated by a white dot must be consecutive.
• Digits separated by a black dot must have a ratio of 2:1.
• Not all dots are given.

Example: Below is a 6x6 example puzzle that you can solve online (Penpa, F-Puzzles, CTC).

Solve Online:

• CTC (or Intergalactic version)
• F-Puzzles (or Intergalactic version)
• Penpa+ (answer check on blue Sudoku)