• Fill every row, every column and every 3x3 box with the digits 1 to 9, no repeats.
• Tap a square, then tap a number. Tap the same number again to clear it.
• Notes puts small pencil marks in a square so you can keep track of the candidates.
• Hint fills in one correct square for you. You get three per puzzle.
• A wrong digit turns red and counts as a slip, but the puzzle carries on.
• The number pad shows how many of each digit are still missing.

Keyboard: 1-9 to write, arrows to move, Backspace to erase, N for notes.

Every puzzle here is generated fresh and checked to have exactly one solution, so it can always be worked out by logic alone - no guessing needed.