Niner is a beautiful, calm sudoku for people who love the puzzle — not the ads, pop-ups, and telemetry that clutter so many other apps.

Open the app. Solve today's puzzle. Close the app. That's the loop.

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WHAT'S INSIDE
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◆ One daily puzzle — same one for everyone, every day
◆ Five difficulties — Beginner, Easy, Medium, Hard, Expert
◆ Five modes — Classic, Strict, Coach, Speed, Killer
◆ 16 achievements, from your first win to "Cage Master"
◆ Daily-streak tracking with a 12-week activity heatmap
◆ Best-time tracking per difficulty + per mode
◆ Five colour themes, each with a hand-tuned dark variant
◆ Six celebration styles, including one minimal option for people who don't want confetti

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GAME MODES
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Classic — the standard experience. Three mistakes, a handful of hints, all the time in the world.

Strict — one mistake and it's over. For players who want their accuracy to actually matter.

Coach — unlimited hints and mistakes. For learning, or for kids who are just starting out.

Speed — race yourself. Your time is the score, and every second counts.

Killer — cages with target sums layered on top. A fresh twist for when you want something new.

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DESIGNED FOR FOCUS
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◆ No ads. None. Not even a "remove ads" upsell.
◆ No account. No login. No email address required.
◆ No internet permission. Niner literally cannot phone home.
◆ No third-party SDKs — no analytics, no trackers, no crash reporters.
◆ No dark patterns — no push notifications nagging you to come back.

Your progress lives on your device, in one tidy SharedPreferences file. Uninstall the app and it's gone — no cloud, no lingering data.

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THOUGHTFUL TOUCHES
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◆ Wrong entries don't get stuck on the board — they shake and vanish. Your board always reflects what you know.
◆ Peer and same-digit highlighting make hard puzzles manageable without making easy ones boring.
◆ Colour-blind palette option for hints and errors.
◆ Large-text toggle for easier reading.
◆ Centered-notes toggle if you prefer a single-row pencil-mark style.
◆ The daily puzzle is deterministic — if you compare notes with a friend, they had the same puzzle you did.
◆ Adaptive launcher icon, proper dark mode, tasteful haptics.

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FOR EVERY LEVEL
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New to sudoku? Start on Beginner with Coach mode — unlimited hints and mistakes, with explanations. Work up from there.

Returning player? Skip straight to Expert or try Speed mode to see how fast you can go.

Just want a daily ritual? The daily puzzle is a fixed Medium difficulty — one puzzle, a few minutes, no decisions.

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BUILT WITH CARE
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Kotlin, Jetpack Compose, Material 3. Puzzle generator runs on-device with a proper uniqueness check, so every puzzle has exactly one solution. No pre-bundled puzzle pack.

Made by one developer, for people who love sudoku.