1# Sudoku23Classic 9x9 number placement puzzle.4567## How to Play89Fill every empty cell with a digit from 1 to 9 so that each row, each10column, and each 3x3 box contains every digit exactly once. Pre-filled11cells (shown in bold) cannot be changed. Conflicting cells are highlighted12in red.1314## Controls1516| Key | Action |17|-----|--------|18| Arrow keys / WASD / hjkl | Move cursor |19| Mouse left-click | Focus a cell |20| `1`-`9` | Fill cell with digit |21| `Backspace` | Clear cell |22| `Ctrl+R` | Reset puzzle |23| `Ctrl+H` | Toggle full help |24| `Escape` | Return to main menu |2526## Modes2728| Mode | Clues | Description |29|------|-------|-------------|30| Beginner | 45 | Single Candidate / Scanning |31| Easy | 38 | Naked Singles |32| Medium | 32 | Hidden Pairs / Pointing |33| Hard | 27 | Box-Line Reduction / Triples |34| Expert | 22 | X-Wing / Y-Wing |35| Diabolical | 17 | Swordfish / XY-Chains |3637## Elo Difficulty3839Named modes are compatibility presets. Use `--difficulty <0..3000>` to target a40specific Elo difficulty for generated puzzles.4142## Quick Start4344```bash45puzzletea new sudoku beginner46puzzletea new sudoku medium47puzzletea new sudoku diabolical48```