The design was a bit tricky. I had a different layout in mind, but I couldn't find a way to get that layout unique without giving digits around a clue. That was something I was trying to avoid as I think these Quad Sudokus look nicer when there are no digits given around the Quad clues. I changed the layout a bit in the left top and right bottom nonet. Originally the right bottom nonet was to get a Quad clue as well, but there was no way to force the 5 with such a clue. I needed that 5 for uniqueness. I still think it's a nice looking puzzle and it should be a good solve.
Rules for Sudoku
In this Sudoku, a clue given on a grid point indicates that no two of the four digits around it have this difference. E.g. a 3 clue indicates that no two of the four digits around it have a difference of 3.
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