Fill the grid so every row, every column and every three-by-three box contains one to nine, once each. Pencil notes, undo and hints included — and every puzzle has exactly one solution.
Every row, column and 3×3 box holds each digit exactly once.
Tap a square, then tap a number. Tap the same number again to clear it.
Turn on Notes to jot the candidates for a square before committing.
A hint fills the selected square. Three per puzzle, so spend them well.
Every puzzle is checked as it is built — no guessing between two answers.
Your quickest time for each level is kept on this device.