Classic Sudoku
The original 9×9 puzzle. Row, column, and 3×3 box must each contain the digits 1–9.
What makes it Stillgrid
Difficulty is graded by the solving technique a puzzle actually requires — not generated by a clue count or stopwatch. An "easy" puzzle solves with naked and hidden singles. "Medium" pulls in pairs and pointing logic. "Hard" needs X-Wing. "Diabolical" needs Swordfish or XY-Wing. You always know what you're walking into.
Rules
- Fill every cell with a digit 1–9.
- No repeats within a row.
- No repeats within a column.
- No repeats within any 3×3 box.
How Stillgrid plays
- Pencil marks (candidates) on every cell.
- Undo/redo with full history.
- Auto-pencil one tap away if you don't want to track candidates by hand.
- Daily challenge with streak tracking — same puzzle for everyone.
- Personal bests for each difficulty.
- Free to play. No signup needed to play.
Common questions
What is classic sudoku?
Classic sudoku is a 9×9 grid puzzle. Fill every cell with a digit from 1 to 9 so that each row, each column, and each of the nine 3×3 boxes contains all nine digits exactly once. The puzzle starts with some cells filled in, and a valid puzzle has exactly one solution.
How is sudoku difficulty decided on Stillgrid?
Stillgrid grades each puzzle by the hardest solving technique it actually requires, not by how many digits are given. Easy solves with naked and hidden singles, Medium needs pairs and pointing, Hard needs X-Wing, and Diabolical needs Swordfish or XY-Wing.
Does Stillgrid show ads?
No. Stillgrid has no ads and no signup is needed to play. Your progress stays on your device.
Is Stillgrid free?
Yes. Every puzzle and variant is free to play, with no signup needed to start a puzzle.