Logic Masters Deutschland e.V.

Normal sudoku rules apply.

Disjoint Groups: Cells with the same position within the boxes contain all the numbers 1 to 9.

Anti-knight 5's: Cells separated by a knight's move cannot both contain 5.

Marked Cells: Mark 1 cell in each box. The digit in a marked cell is it's position in the box (read like a book: left to right, top to bottom).

Indexing: Row 1 and column 1 index these marked cells as follows: if rXcY is a marked cell, then r1cY contains the digit X and rXc1 contains the digit Y. See the example image below for reference.

Play in the CTC App

Sample of indexing and marked cells: