Logic Masters Deutschland e.V.

I was torn between 4* and 5* for this puzzle's difficulty as it's certainly not a walk in the park, and erred on the side of 4* because I've definitely made plenty of much harder puzzles. I also didn't originally include the given 9, and the puzzle is just about possible without it, so after my incredibly rare generosity of actually giving a not-strictly-necessary digit, there was no way I could rate it 5*!

And yes, I'm aware that two of the lines are entirely useless. But how could I resist the rainbow spiral?


Normal sudoku rules apply.

Region borders divide lines into line segments. On each line, the sum of each line segment must strictly ascend from one end to another.

White dots join consecutive digits.