Logic Masters Deutschland e.V.

Rules
Normal sudoku rules apply.
Digits cannot repeat on the negative diagonal.
There are nine copycat cells in the grid, one in every row, column and box. Each digit from 1-9 appears in a copycat cell exactly once.
A copycat cell's value is equal to the digit in the cell with opposite coordinates (i.e. mirrored by the diagonal).
For example, if r8c3 is a copycat cell, its value is equal to the digit in r3c8.
The sum of the values along an arrow is equal to the value in the connected circle.

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