Logic Masters Deutschland e.V.

Normal sudoku rules apply.

Every 7 in the grid must be a chess king's move away from an 8 which is a king's move from a 9, thus forming the sequence 789. Different 7s may share the same 8 and/or 9. (ie the rule applies to every 7 but not necessarily every 8 or 9).

Because 7 ate 9 the following rules also apply:
7 has grown by 9, so 7 = 16.
9 has been eaten, so 9 = 0.
6 is afraid of 7, so does not appear in any of the eight cells surrounding a 7.

Digits within cages sum to the number in the top left corner (remembering that 7 ate 9).

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