Fill every empty cell with a digit 1–9. The same three rules apply everywhere on the grid.
Each digit 1–9 appears exactly once in every row, every column, and every bold-bordered 3×3 box.
- Given numbers are fixed and can't be changed — only the empty cells are yours to fill.
- Tap a cell, then a digit, to place it. Tap again to change it.
- Turn on ✎ Notes (or press N) to pencil small candidate digits into a cell; tap a digit again to remove it. Placing a number clears it from the notes in its row, column and box.
- Tap any number — on the keypad or on the board — to light up every copy of it on the grid.
- Everyone races the same puzzle at once — first to fill the grid correctly wins.
