Sudoku
Freshly generated boards with a single valid solution. Notes, error check, timer.
Frequently asked questions
Are these real single-solution puzzles?
Yes. Each board starts from a full valid grid, then clues are removed only while a solver confirms exactly one solution remains. Guessing is never required on easy and rarely on hard.
What makes a puzzle easy or hard here?
The number of starting clues: easy keeps around 40, medium about 32, hard drops to the high 20s. Fewer clues force longer deduction chains.
How do pencil notes work?
Toggle notes mode and tap numbers to mark candidates in a cell. Entering a real number clears that cell's notes. Notes are visual aids only; the checker ignores them.
Does the error check spoil the puzzle?
It only flags numbers that conflict with the current board (same row, column, or box), not numbers that merely differ from the final solution, so it catches slips without solving anything for you.