Sudoku Duo

Goal: Fill the shared grid together so every row, column and 3×3 box holds 1–9 with no repeats.

Together: It's co-op — either of you can fill, change or erase any non-clue cell at any time (you can replace each other's entries). You both see the same board live.

Entering: Tap a cell, then a number to place it. Any digit goes in — if it clashes with the same number in its row, column or box, both cells turn red so you can fix them.

Pencil marks: Turn on ✏️ Pencil to jot a small "maybe" in a cell (you both see it); turn Pencil off and tap a number to confirm it into a real entry.

Winning: You win the moment every cell is correct — there's no score, just the solve (and the clock).