Negative Constraint Sudoku
The rule: Every kropki dot is given. Black: one digit is double the other; white: consecutive. An unmarked pair is neither.
Play unlimited Negative Constraint puzzles free — every one generated with a unique solution, rated by the solving techniques it actually needs.
- Four difficulties, from gentle to expert
- Step-by-step hints that teach, not just tell
- Interactive lessons and a daily race
- Make and share your own puzzles