Four levels and a daily puzzle
Easy, Medium, Hard and Expert, plus a new Daily puzzle every day with a streak to keep going.
Notes that keep up
Pencil marks clear themselves when you place a digit, and matching digits, rows, columns and boxes light up.
Hints that teach
A hint fills in the easiest cell to solve next, or fixes the one you picked. Undo, erase and a mistake limit you can turn off.
Watch yourself improve
Best and average times for each level, win streaks and perfect games, with light and dark themes.
Your games stay yours
Sudofold has no account and asks for no permissions. Your games and statistics stay on your phone. The app is free with ads from Google AdMob, which never see your games.
Guides
Sudoku rules, strategies and tips, from your first puzzle to Expert.
- How to play sudoku: the rules and how to solve your first puzzle
The three sudoku rules in plain words, how to find your first digits, when to use notes, and what to do when you get stuck. No maths needed.
- Sudoku strategies for beginners: 6 techniques that solve most puzzles
Six sudoku techniques in the order you'll need them, from hidden singles to pointing pairs, each with a simple example. Enough to solve Easy to Hard puzzles.
- How to use notes (pencil marks) in sudoku
When to start writing notes in a sudoku, the two ways to write them, how to keep them correct, and the patterns that notes help you find.
Questions
Is Sudofold free?
Yes, and there is no account to create. It shows a banner under the home screen and under the board, and now and then a full-screen ad when you leave a finished game. Videos are optional: watch one for an extra hint after the 3 free ones, or for a second chance after your third mistake.
Does every puzzle have one solution?
Yes. Each puzzle is made on your phone and checked so that exactly one grid fits it. That means you can always solve it by logic; you never have to guess.
What's the difference between the levels?
Easy (about 40 given digits) and Medium (about 32) can always be solved with singles: a cell with only one possible digit, or a digit with only one possible place in a row, column or box. Hard (about 27) and Expert (about 23) start with fewer digits and need more than singles, such as pairs found with notes. The Daily puzzle is Medium, and it's the same for everyone that day.
How do hints work?
A hint fills in one cell: the cell you've selected if it's empty or wrong, otherwise the empty cell with the fewest possible digits, which is the easiest place to make progress. You get 3 free hints per puzzle.
Can I play offline?
Yes. Puzzles are made on your phone, so you can play anywhere. Ads need a connection, but the game doesn't.
Which phones and languages does it support?
Android 8.0 or newer, phones and tablets, in portrait and landscape. The app is in English, Spanish, Portuguese, French and German.