How to Play

Fill the 9×9 grid so that every row, every column, and every 3×3 box contains the digits 1–9 exactly once.

• Grey cells with bold digits are givens — they cannot be changed.
• Tap a cell to select it, then tap a digit on the on-screen pad (or use a keyboard on desktop).
• Use the three entry modes above the digit pad: Answer (large #) places a digit, Corner mark (small # top-left) toggles corner notes, and Centre mark (small # in the middle) toggles centre notes.
• Clear removes a placed digit and restores any marks that were in that cell; if the cell has no digit, Clear removes its marks.
• Undo (or Ctrl/Cmd+Z) reverses your recent moves in this session.
• Cells that conflict with another digit in the same row, column, or box are highlighted.
• When the grid is complete and valid, your time is submitted automatically if you are signed in.

Difficulty

Each day uses one difficulty — easy, medium, or hard — chosen at random for that date. Difficulty is based on the solving techniques required, not just how many clues are given.
I intend these puzzles to be within reach of the everyday puzzler and be roughly the same difficulties as an average book of Sudokus.

Scoring

Leaderboard ranking is by solve time only. Your first successful finish for the day is recorded; later finishes do not replace it.