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.
- Everyone races the same puzzle at once — first to fill the grid correctly wins.
