Sudooku is a clean, ad-free Sudoku puzzle game for Android. Built for people who just want to solve puzzles — no popups, no trackers, no nagging you to rate it. Just a well-made sudoku that lives on your device and nowhere else.

DIFFICULTY FOR EVERY MOOD

• Kids (4×4) — a gentler grid for little ones learning sudoku logic
• Easy, Medium, Hard, Expert, Master (9×9) — the full spectrum, from a coffee-break solve to a serious puzzle
• Daily Challenge — one puzzle a day, same for everyone, with difficulty rotating through the week (Monday Easy → Sunday Master)

REAL FEEDBACK WHILE YOU SOLVE

• Live validation: wrong placements flag red the moment you make them (or turn it off for a pure-logic run)
• Mistake counter with an adjustable cap — 3, 5, or unlimited
• Smart hints name the technique they used — Naked Single or Hidden Single in row / column / box — so repeated hints teach the pattern
• Auto-complete cascades the board when every remaining cell is logically forced (toggleable)
• Auto-note button fills every empty cell with its candidate digits in one tap

TWO INPUT MODES

• Cell-first — tap a cell, then the digit (classic)
• Number-first — tap a digit, then drop it onto cells. Notes for the armed digit highlight across the board while other notes fade, so "where can this number still go?" is a single glance

STATS AND STREAKS

• Per-difficulty win streak shown right on the home screen
• Best time this week for every difficulty
• Daily Challenge calendar with current and longest streak
• Sixteen local achievements — no account, no sign-in
• Full statistics: best time, average time, wins, average mistakes, hints used

PICK YOUR LOOK

• Four board palettes — Classic, Paper, Ocean, Forest
• Light, Dark, or Follow-system theme
• Themed launcher icon on Android 13+

BUILT FOR FOCUS

• No ads. No tracking. No network access at all.
• Offline from day one — everything lives on your device
• Keep-screen-on toggle while playing
• Pencil notes with optional auto-remove when you place a digit
• Pause, resume, unlimited per-game undo / redo
• Big-number-entry accessibility mode

TEACHING, NOT SPOILING

Sudoku techniques reference built in — learn about Naked Singles, Hidden Singles, Locked Candidates, Naked Pairs, Hidden Pairs, and the X-Wing. The hint engine tries the easiest technique first and names it so you can spot it yourself next time.

PRIVACY

Sudooku collects nothing. Not play history, not device info, not analytics. The app has zero permissions declared and no internet access. Your stats and saves are stored only on your device.

Built with native Kotlin and Jetpack Compose for fast startup and a small footprint.