Logic Masters Deutschland e.V.

Normal sudoku rules apply.

Draw a loop in the grid that visits every 3x3 box except for the center (box 5).

The central 3x3 box is a magic square, meaning that each row, column, and main diagonal adds up to the same number.

The loop may touch itself orthogonally and diagonally, but may only move orthogonally. The loop does not branch, visit any 3x3 box more than once, or pass through any cells connected by a black dot.

Cells connected by black dots must be in a 1:2 ratio and not all such dots are given.

The loop is a standard region sum line wherein 3x3 box borders divide it into segments with the same sum. This particular sum is one of the numbers given in the puzzle.

Little killer clues outside of the grid give the sum of their indicated diagonals.

SudokuPad link