It isn’t as easy as 1-2-3-4. Or, it’s as easy as isn’t 1-2-3-4. It’s hard to express things in negative terms! The point is: If all of those anti-quad clues were normal quadruples clues, well, this puzzle would be broken. But also, it would be incredibly easy. However, they’re not quads, they’re anti-quads, so they provide slightly less information, keeping this puzzle fun.
Rules:
Normal Sudoku rules apply.
Digits within uncolored circles appear at least once in cells touching the circle. Digits within colored circles do not appear in cells touching the circle.
Estimated difficulty: 2 out of 5
Solve on SudokuPad