Sudoku - Classic Sudoku Puzzle

Sudoku Classic is a clean, calm, distraction-free take on the classic 9x9 number puzzle. No clutter, no pop-ups, no sign-in — just you and the grid. Every puzzle is generated on your device and has exactly one solution, so you can always solve it by pure logic. The app works completely offline and collects nothing: no account, no ads, no tracking.

★ FIVE DIFFICULTY LEVELS
Easy, Medium, Hard, Expert and Master. Difficulty is graded by the human solving techniques a puzzle actually needs — from naked and hidden singles up to pointing pairs, box/line reductions, triples and X-Wing — not just by how many clues are showing. So an "Easy" is genuinely gentle and a "Master" is a real test.

★ DAILY CHALLENGE
A new puzzle every day, the same for everyone, generated offline from the date. Build a streak on the calendar and aim to complete a whole month.

★ BUILT FOR FOCUSED SOLVING
• Clean, highly legible board with clear 3x3 boxes
• Tap a cell to highlight its row, column, box and all matching digits
• Pencil notes (candidates) with automatic clean-up when you place a digit
• Unlimited undo and redo, including note edits
• Erase, and a configurable mistake limit (or turn it off entirely)
• Smart hints that reveal one correct cell AND name the technique, so you learn
• Long-press a number to lock it for fast fill

★ MAKE IT YOURS
• Light and dark themes, plus Paper, Midnight, Slate and Sepia board styles
• Adjustable number size
• Toggle mistake-checking, duplicate highlighting, same-digit highlighting, auto-removing notes, the timer, sound and haptics
• Cell-first or number-first input

★ TRACK YOUR PROGRESS
Per-difficulty statistics: games started and won, win rate, best and average time, current and best streaks, and perfect wins (no mistakes, no hints).

★ PICK UP WHERE YOU LEFT OFF
Your game is saved automatically and survives closing the app, rotating or rebooting — the grid, your notes, the timer and your full undo history are all restored.

★ PRIVACY FIRST
100% offline. No internet permission. No accounts. No analytics. No ads. Nothing you do ever leaves your phone.

★ ACCESSIBLE
Full TalkBack support with per-cell labels, large-font support, and colour-blind-safe error marking (a conflicting digit is underlined, never shown by colour alone).

Phones and tablets supported, in portrait and landscape.