Sudoku Zen is a calm, ad-free Sudoku game built for thinkers who want to slow down. A hand-drawn aesthetic, an adaptive difficulty engine, and a smart-hint system that actually teaches the techniques — it's Sudoku for people who care about how they solve, not just whether they solve.

SEVEN DIFFICULTY TIERS, ONE SMOOTH LADDER

Hand-graded puzzles carry you from your first solve to expert territory:

• Easy — Naked Singles
• Medium — Hidden Singles
• Hard — Naked Pair, Hidden Pair, Pointing Pair
• Tough — Naked Triple, Hidden Triple, Claiming
• Expert — X-Wing
• Fiendish — XY-Wing, Simple Coloring
• Master — Swordfish

Every puzzle is generated to require exactly the technique its tier demands — no fluking your way through Master with a lucky guess.

ADAPTIVE DIFFICULTY THAT LEARNS WITH YOU

The home screen suggests your next puzzle based on how you have been playing. Wins move you up, losses move you down. In Classic mode it also names the next technique waiting for you — a target instead of a wall.

THREE GAME MODES

• Classic — entries are validated, three mistakes and you are out
• Casual — entries are validated, unlimited mistakes
• Purist — no validation, no safety net, real Sudoku

THE ZEN AESTHETIC

Cream-paper background, cursive typography, and a hidden timer for when you want to stop racing the clock. Dark mode swaps to a tea-stained parchment palette. Switch between Default (Material 3) and Zen in Settings — the look is independent from the game rules.

SMART HINTS — THE HINTS THAT TEACH

Tap hint and Sudoku Zen names the technique, highlights the pattern cells, lists the eliminations, then lets you reveal, place, or dismiss. The Learn library has a worked example for every technique with a "Try a practice puzzle" button — the generator builds a puzzle that requires exactly that technique, so you actually internalize it.

DAILY PUZZLE + STREAKS

A new daily puzzle every morning, with a weekday difficulty rotation that escalates through the week. Build your daily streak and watch the badge climb on the home screen.

STATS WORTH LOOKING AT

Track wins by mode, by difficulty, and by technique practiced. Practice puzzles are tracked separately so your real stats stay honest. Daily streak history is preserved across sessions, with overall and per-mode breakdowns.

THOUGHTFUL DETAILS

• Pencil marks with auto-clear of peer marks on digit placement (toggle in Settings)
• Auto-pause when you leave the game — Resume is always exactly where you left it
• Undo and Redo
• Mistake feedback with haptic + flash
• Wake-lock toggle to keep the screen on during long sessions
• Resume-friendly save: one in-progress game, always waiting on the home screen

NO ADS, NO ACCOUNTS, NO TRACKING

Everything runs locally on your device. No ads, no sign-up, no analytics watching your shoulders. Just Sudoku.

ACCESSIBILITY

Semantic descriptions on every board cell and keypad button. Long-press tooltips on the top-bar actions. Works with TalkBack.

Built with Jetpack Compose and Material 3 on top of a hand-crafted pure-Kotlin solver.

Made in India by Mango Labs.