Logic Masters Deutschland e.V.

This was part of a Setting Competition held in 2024/2025. The Skunkworks League was hosted by @damasosos92.
The competition took place in a total of 7 turns with a unique prompt for each round. Setter's had to create and test a unique puzzle for each prompt solely by themselves.

As of the prompt for Turn 7 of TSL the goal was to create a QuattroQuadri using only standard constraints. Each constraint had to be only used once and the puzzle had to contain at least 8 of them.


Rules:
Standard rules for the following constraints apply:
QuattroQuadri, German Whisper (green), 3-modular lines (teal), region sum lines (blue), renban lines (pink), parity (odd/even) lines (red), palindromes (grey), killer cages, quadruples, minimum, odd cells.
QuattroQuadri:: Place the digits 1 to 9 once each into the 3x3 boxes. Digits may not repeat in the same row, column, or box.
German Whisper (green):
Two cells connected by a German whisper line must have a difference of at least 5.
3-modular lines (teal):
Every 3 consecutive cells along a 3-modular line must contain a complete set of residuals modulo 3. i.e: one from (3,6,9), one from (1,4,7) and one from (2,5,8).
Region Sum Lines (blue):
For each line, digits on the line have an equal sum N within each box it passes through.
Renban Lines (pink):
Every renban line contains a set of consecutive digits in any order, without repeats.
Parity (odd/even) Lines (red):
Every pair of consecutive cells along a parity line must contain an even and odd digit.
Palindromes (grey):
Digits on a palindrome line read the same forwards and backwards.
Killer Cages:
Digits in cages must sum to the number in the top-left corner and cannot repeat.
Quadruples:
Every digit in a circle has to be assigned to one of the surrounding cells.
Minimum:
Cells with this constraint are smaller than all adjacent cells without this constraint.
Odd:
Cells with grey circles must contain odd numbers.