Logic Masters Deutschland e.V.

Normal sudoku rules apply.

Digits along the marked diagonals may not repeat. In addition, digits on the marked diagonals "index" their box number in their row or column (or both). For example, If R7C7 (in box 9) is a 5, then there is a 9 in at least one of R5C7 or R7C5.

Digits listed in each circle must appear in the four surrounding cells.

CTC link: https://tinyurl.com/CTCIndeX
F-Puzzles link: https://f-puzzles.com/?id=2oyofrc7