Logic Masters Deutschland e.V.

Rules:

• Normal Sudoku rules apply. Place the digits 1 through 9 in each empty cell. Digits must not repeat within the same row, column, or box.
• Box Indexing: The position of digit X in box Y is the same as the position of digit Y in box X.
• Killer: The value of digits within a cage must sum to the number in the top-left corner.

Links:

• F-Puzzles: https://f-puzzles.com/?id=26ux455m
• CtC App: https://tinyurl.com/KillerBoxIndex