Fill the grid so every row, column and box has one to nine. A fresh puzzle every time.
Fill the 9x9 grid so that every row, every column and every 3x3 box contains the digits 1 through 9 exactly once. Tap a cell, then tap a number to fill it. Given numbers are locked and can't be changed. Three wrong entries end the round, so take your time on harder puzzles.
Turn on Notes to pencil in small candidate numbers instead of committing to an answer — tap a number while Notes is on to toggle it in the selected cell's corner grid. If you're stuck, Hint reveals one correct cell, but you only get three per puzzle, so save them for when you're truly stuck.