Logic Masters Deutschland e.V.

This puzzle continues my loop series where Kropki dots are the only given clues. The previous puzzles had the loop be a modular line and an entropic line. The estimated difficulty for this puzzle is between 3 and 4 stars, though I've initially listed it at 4.

Rules:

Normal Sudoku rules apply.

Digits separated by a white dot are consecutive. Digits separated by a black dot have a ratio of 2:1. Not all possible dots are necessarily given.

Draw a one-cell-wide loop of orthogonally connected cells. The loop may not touch itself, not even diagonally.

-- The loop must occupy all cells connected by a given dot.

-- The loop acts as a region sum line. The sum of digits along the loop is the same in each 3x3 region the loop enters. If the loop enters a region multiple times, the sum is counted separately for each segment.

-- Adjacent digits along the loop not connected by a given dot cannot have a Kropki relationship (i.e., they cannot be consecutive or have a ratio of 2:1)