"## ?? Main functions

### Core game features
- **Classic Sudoku gameplay**: 9×9 standard Sudoku grid
- **Multiple difficulty levels**:
- Easy: remove 30 numbers
- Medium: Remove 40 numbers
- Difficulty: Remove 50 numbers
- **Smart Prompt System**: Friendly prompts are provided when a cell is not selected or a fixed number is selected.
- **Game Statistics**: Record game time, moves and best scores

### Custom options
- **Symbol Selection**:
-Number mode: use numbers 1-9
- Alphabet mode: use letters A-I
- **Background Theme**:
- Default gradient background
- pattern background 1
- pattern background 2
- Game-specific backgrounds

### User experience
- **Immersive Status Bar**: Full screen gaming experience
- **Smooth Animation**: Button click feedback, title animation, decorative element animation
- **Game Records**: Save the latest 5 game records
- **Success/Failure Dialog**: Beautiful prompt interface at the end of the game

## ?? Gameplay

### Basic Rules
1. **Goal**: Fill in the numbers (or letters) in the 9×9 grid so that each row, each column, and each 3×3 square contains 1-9 (or A-I)
2. **Rules**:
- Each line can only contain 1-9 (or A-I) once each
- Each column can only contain 1-9 (or A-I) once each
- Each 3×3 square can only contain 1-9 (or A-I) once each
- The initial number (black) cannot be modified
- The number entered by the user (blue) can be modified

### How to operate
1. **Select cells**: Click on any cell in the Sudoku grid
2. **Fill in numbers/letters**: Click the number/letter button at the bottom
3. **Clear Content**: Click the Clear button to delete the contents of the selected cell.
4. **Game Over**: All cells filled or an error occurred

### Game flow
1. Start the game and select the difficulty level
2. Click on a blank cell to select
3. Use the buttons at the bottom to fill in the corresponding numbers/letters
4. Continue filling until the entire grid is complete
5. Display completion dialog box and statistical information when the game is successful

## ⚙️ Setting options

### Difficulty setting
- **Easy**: suitable for beginners, remove 30 numbers
- **Medium**: Standard difficulty, remove 40 numbers
- **Hard**: Challenge mode, remove 50 numbers

### Symbol settings
- **Number Mode**: Traditional 1-9 numbers
- **Letter Mode**: A-I letters, added game changes

### Background settings
- **Default Background**: classic gradient background
- **Pattern Background 1**: Simple geometric pattern
- **Pattern Background 2**: Soft gradient colors
- **Game Background**: Dedicated game theme background"