1# Sudoku23Fill a 9x9 grid with digits so every row, column, and box is complete.45## Rules67- Each **row** must contain the digits 1 through 9 exactly once.8- Each **column** must contain the digits 1 through 9 exactly once.9- Each **3x3 box** must contain the digits 1 through 9 exactly once.10- Pre-filled cells (shown in **bold**) cannot be changed. Conflicting11 cells are highlighted in red.1213## Controls1415| Key | Action |16|-----|--------|17| `Arrows` / `wasd` / `hjkl` | Move cursor |18| `Mouse left-click` | Focus a cell |19| `1`-`9` | Fill cell with digit |20| `Backspace` | Clear cell |21| `Ctrl+H` | Toggle full help |22| `Ctrl+R` | Reset puzzle |23| `Escape` | Return to main menu |2425## Tips2627- **Scan the most-filled groups first.** Rows, columns, or boxes that28 already have seven or eight digits filled leave very few possibilities29 for the remaining cells, making them the easiest to solve.30- **Look for naked singles.** If a cell has only one digit that doesn't31 conflict with its row, column, and box, that digit is the only option.32 Check the most constrained cells before guessing anywhere.33- **Use the conflict highlighting.** When you place a digit, conflicting34 cells turn red immediately. Catch mistakes early so they don't cascade35 across the board.