The basics
Fill the 9×9 grid so every row, every column, and each 3×3 box contains the digits 1–9 exactly once. Tap a cell, then choose a number — conflicts highlight instantly. (The X level also needs both diagonals to hold 1–9.)
Create
Create Game makes a fresh puzzle at your chosen level, or lets you build your own.
Zen
Zen opens an immersive full-screen view so you can focus.
Erase · Undo · Redo
Erase clears the selected cell. Undo steps back through your moves and Redo replays them — up to 28 steps. The starting clues are locked and can't be changed.
Notes
Not sure of a number yet? Turn on Notes to pencil small candidate digits into a cell. Tap a digit to add or remove it; placing a real number clears that cell's notes.
Timer & Pause
A countdown runs while you play — set its length in Settings. Tap ⏸ Pause to hide the board and stop the clock, then Continue to resume. When it reaches 00:00 the grid freezes.
Hint
(Available only for puzzles with a unique solution.)
Tap 💡 Hint to spotlight the next cell to solve. Tap 💡 again to remove the spotlight and try filling it yourself. Still stuck? Tap 💡 again, then tap the highlighted cell to reveal its value. Cells revealed using Hint are underlined to distinguish them from the digits you entered yourself.
Voice (beta)
Play hands-free: tap the 🎤 mic and speak — “row 3 column 5 seven” (or three numbers “1 2 5” = row, column, value), a lone “seven”, “up / down / left / right”, “erase”, “undo”, “redo”, or “notes”. Works in Chrome, Edge, and Safari.