Each puzzle has one solution
The puzzle generator creates a board with one valid solution at the selected difficulty.
All projectsStill SudokuEasy · Assist example
Still Sudoku
Play Sudoku at your own pace
Play Sudoku at four difficulty levels, use notes and hints, and choose how the app flags mistakes.
Interactive example · sample data
Select an empty square, then choose a number.
Still Sudoku offers four difficulty levels, notes and undo and redo controls. Choose how strictly the game flags mistakes.
Available on iPhone and Android · iOS / AndroidChoose the kind of help you want.
- Strict
- Flags errors
- Assist
- Offers guidance
- Zen
- No mistake alerts
Choose how mistakes are handled
Strict flags errors, Assist offers guidance and Zen lets you solve without mistake alerts.
How we built it.
Still Sudoku combines a generated puzzle with the small controls that make a long solve comfortable. The puzzle logic and the interface state are kept separate.
A board you can work through
Pencil notes belong to individual cells, and move history supports both undo and redo. Placing a number can remove related notes, while row, column and box highlighting helps the player keep their place. Pause and resume let a puzzle continue around interruptions instead of requiring one uninterrupted sitting.
A daily puzzle and a lasting record
The daily puzzle is seeded by date. Game history, statistics, achievements, settings and themes are stored alongside the current puzzle state. A persisted Zustand store backed by AsyncStorage keeps those pieces together, including entries, notes and the undo/redo stacks.
Generation is separate from presentation
The JavaScript engine fills a valid board using backtracking, then removes clues while checking the number of possible solutions. Expo and React Native render the mobile experience, while the pure engine can be tested without navigating the app. That separation makes puzzle correctness a distinct concern from visual themes and progression.
Built with
- JavaScript
- Expo
- React Native
- Expo Router
- Zustand
- AsyncStorage