Sudoku online with hints that explain every step

By the hardest technique its easiest solution needs, not by the number of given digits. A solver that works like a person goes through every new puzzle: if scanning for a digit’s only place is enough, the puzzle is easy; if it also needs cells with a single option, it is medium; pairs and locked digits make it hard; triples, X-Wing, Skyscraper and XY-Wing — expert; Swordfish, W-Wing, coloring and XY-chains — master. A puzzle that would need a harder technique than its level allows is not handed out.

No. A clue is removed from a new puzzle only while the logic solver can still finish the board with the techniques of the chosen level, so every puzzle can be solved step by step and has exactly one solution. The exhaustive solver confirms the single solution once more before the puzzle is shown.

Because a hint builds on the board as it stands. If one of your digits does not match the solution, every later deduction would be false, so the hint points at that digit first. The same happens in automatic notes when you have crossed out the digit that actually belongs in a cell.

The page tells you so and marks the cells where two of the solutions differ. That is usually where a clue was left out or mistyped, so compare those cells with the source first. A puzzle with no solution, or with a digit repeated in a row, column or box, is also reported before the game starts.

Yes. The puzzle is built from the date and the level, so two people who open the same level on the same calendar day get the same board. It changes at your local midnight, and the calendar keeps the earlier days open.

The best time and the average count only games finished without hints. A game where Hint, Check or the step-by-step solution was used is still counted as played and solved, and the result screen says that the record was left as it was.