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.
Scan one row, column or 3x3 box at a time rather than jumping around the whole grid — it's much easier to spot which numbers are missing that way. Use Notes mode to pencil in every possible candidate for a tricky cell, then eliminate them one by one as neighbouring cells fill in. Save your three hints for when you're genuinely stuck rather than using them early on easy deductions.
Are the puzzles guaranteed to have only one solution? Yes — every puzzle is generated and checked to have exactly one valid solution before it's given to you.
What happens after three mistakes? The round ends and the full solution is revealed on the board.
Which difficulty should I start with? Easy aims to leave more starting digits than Medium or Hard. The generator retains extra clues when needed to preserve a unique solution, so the exact count can vary.
Every row, column and 3×3 box needs the digits one through nine without repeats. Choose a cell and compare all three groups before entering a value. Notes let you record candidates while you reason. They are possibilities, so remove candidates when a neighbouring placement makes them impossible. Filling a cell because its digit is missing from the row alone ignores the column and box constraints.
Suppose a row is missing only 2 and 7, leaving two empty cells. For one of those cells, its column already contains a 7. That cell must therefore be 2, and the other empty cell in the row must be 7, provided the box constraints agree. The useful step is explaining why one candidate is impossible, rather than trying both and watching the mistake counter.
This version allows three hints and ends a round after three wrong entries. Given digits are locked. Hints reveal a correct entry; use them to understand an obstacle rather than comparing a hint-assisted time with a completely unaided run.
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