Logic Masters Deutschland e.V.

This is an official entry to the Dutch Flat Mates series started by Flinty.

Here's the link to Flinty's spreadsheet with the list of puzzles in the series.

• Normal sudoku rules apply.
• Dutch Flat Mates: Every 5 in the grid must have a 1 directly above it or a 9 directly below it. It may have both, but it doesn’t need both.
• Full Quad-Rank:
  • All the 2x2 areas of the grid, when read in western reading order, make a total of 64 four-digit numbers.
  • Clues in the center of a 2x2 area show its rank among those 64 numbers, where the lowest is 1 and the highest is 64.
  • One or more equal numbers are considered to be at rank N when there are N-1 numbers of strictly lower rank. (For example, we say there are three numbers in rank 20 when there are 19 numbers of lower rank and the next rank will be 23, i.e. the ranks could go ⋯, 19, 20, 20, 20, 23, ⋯)
  • The letter X stands for a positive integer number.

Online in Sudokupad

Hint: (highlight below)

See also:

• zauberschein
• watskeburt
• diploptic triptych
• huisgenoot gezocht
• bewuste sabotage
• Top Right Boi
• dissipation gradation