Classic Sudoku - Zero to Hero

Code Smart AB

About this game

Welcome to a fresh and engaging Sudoku experience!
This app blends the classic logic puzzle with a clean design and tools that help you improve. Whether you’re new or a pro, you’ll find the perfect challenge.

Features

Five difficulty levels — from Easy to Insane.

Smart hint system — a gentle nudge without spoiling everything.

Learning engine — learn techniques (Hidden/Naked Singles, X-Wing, etc.) with explanations.

Pencil notes — track small candidates in each cell, just like on paper.

Magic Pencil — auto-fill reasonable candidates with one tap.

Handwriting (Digital Ink) — write the digit; the app recognizes and fills it in.

Color themes — choose Green, Blue, or Lavender in light/dark mode.

Undo & Erase — experiment freely.

Auto-save — continue where you left off.

Offline — play without an internet connection.

Ad control

No forced ads. All ads are optional (rewarded).

Some bonuses (e.g., extra hint) can also be unlocked via an optional rewarded ad — your choice.

How to play
Fill the 9×9 grid so that every row, column, and 3×3 box contains the digits 1–9. Use logic — and the built-in tools — to master each board.