Lantern Sudoku

Lantern Sudoku is a quiet sudoku for short, calm sessions. It has no ads, no account and no game over, and it works fully offline.

When you're stuck, a hint lights the next step instead of giving the answer away. You choose how much help you want:
• Where to look: the area where the next step is.
• Why: the technique by name, with a short explanation and the cells that matter highlighted.
• The digit, only if you want it.
If a digit on the board is wrong, the hint tells you that first, so you never chase a step built on a mistake.

Honest puzzles
• Four levels: Easy, Medium, Hard and Expert.
• Every puzzle has exactly one solution and never needs guessing.
• Each puzzle is graded by the hardest technique it needs, so a level means the same thing every time.
• More than 11,000 puzzles come with the app. Nothing is downloaded.

A daily puzzle
• One puzzle a day, the same for everyone, with a streak and days played.
• Share a spoiler-free result card if you like. Nothing is shared unless you tap Share.

Made to be easy on the eyes
• Large, clear digits, with a Larger digits option.
• Light, Dark and two high-contrast themes.
• Works with large system text and with TalkBack.

Never punished
• Mistakes can be shown or hidden. A mistake limit is optional and off by default.
• Your game is saved after every move. Undo, redo, erase and notes that tidy themselves when you place a digit.
• A calm summary when you finish, and statistics per level.

Private by design
• No ads, no analytics, no crash reporting, no account.
• The app asks for no permissions, not even internet access.
• Your games stay on your phone. If Android backup is on, Android may copy them to your own Google account; the app itself never uploads anything.

Lantern Sudoku is free and open source software (GPL-3.0-or-later).

First release.

• Four honest levels, every puzzle unique and no-guess, graded by technique.
• Hints that teach: where to look, why, then the digit if you want it. Learn pages for every technique.
• A daily puzzle with a streak, past days to catch up, and a spoiler-free share card.
• Large digits, Light, Dark and high-contrast themes, TalkBack support.
• No ads, no account, no permissions, fully offline.