Logic Masters Deutschland e.V.

This started as a proof of concept, but I'm quite pleased with how it turned out. Thanks to everyone who tested! If you aren't already comfortable with index lines, this might be a tough place to start. I heartily recommend Marty Sear's puzzle where he introduced them! All feedback, whether complimentary or critical is appreciated. Thanks for playing!

Rules:

Sudoku: Place the digits 1-9 once each in every row, column, and box

Quads: A digit inside of a circle must appear in one of the four cells touching that circle.

Mod-Length Index Lines: Along a line that is N cells long, the digit, D, that is placed in a cell will have a value equal to D modulo N (i.e. the remainder of D divided by N). If D is a multiple of N, it will have a value equal to N, rather than zero.

Along the line, if a digit in position U has value V, then the digit in position V must have value U. The diamond marks which end of the line is position 1.

For example, a line of length 4 consisting of the digits 6938, starting from the diamond, would have values 2134. This would be a valid line, because the value of 2 in position 1 is matched by a value of 1 in position 2, the 3rd position is satisfied by its own value of 3, and so on.

Coloring is purely cosmetic and simply tracks lines of the same length.

Click the puzzle to play!