Logic Masters Deutschland e.V.

Place the digits 1-9 exactly once in each row, column, and 3x3 box. Digits in blue diamonds directly connected (i.e., continuing straight at junctions and stopping at any intermediate diamonds) by blue lines differ by at least 4. The digits along a blue line between two diamonds are not between the digits that appear in the diamonds.

Play in Sudokupad

There is also a harder version with the same solution but fewer clues.