Logic Masters Deutschland e.V.

This is a puzzle that I created for the Quads on Parade puzzle pack hosted by BremSter and the Sudoku Skunkworks. This pack is free to download, and I highly recommend checking it out! Note that the rules in this version are slightly different than the ones presented in the pack, and were edited to clarify how cells outside the grid work. The puzzle itself is unchanged.

Ratings, comments, and feedback are much appreciated! Please feel free to reach out to me on Discord if you have any comments or questions. Please also feel free to try my other puzzles here.

Rules:

• Within the 9x9 sudoku grid (white cells), place the digits 1 to 9 such that digits do not repeat in any row, column, or 3x3 box.
• Sandwich: Gray cells outside the 9x9 sudoku grid indicate the sum of the digits between the 1 and the 9 in their corresponding row or column. The solver must place valid sandwich clues (numbers 0 to 35) in some of the gray cells outside the 9x9 grid. The only sandwich clues that need to be placed are ones that are forced by Kropki dots or Quadruples clues.
• Quadruples: Quadruples circles contain one or more single-digit numbers which must be placed at least once in the (up to) four cells touching that circle (including gray cells outside the 9x9 sudoku grid).
• Kropki pairs: Numbers separated by a white dot are consecutive, and numbers separated by a black dot have a 1:2 ratio. Not all dots are given.
• For clarity, the black cells in the corners are not part of the puzzle, and cannot contain numbers. Additionally, numbers placed in gray cells do not affect solution check.

SudokuPad: https://sudokupad.app/uo2i8xc0xr