Logic Masters Deutschland e.V.

Rules:Normal sudoku rules apply. Digits along an arrow sum to it's circle. In cages, digits sum to the total in top left corner, digits may repeat if allowed by other rules. Digits separated by a King's move (in chess) cannot contain the same digit.

Every row, column and 3x3 box has exactly one doubler, and are a set of the digits 1-9. Cells that are doublers are neither within a King’s move nor a Knight’s move (in chess) of each other.

Solve on CTC