1. Launch Sudoku Royal on your mobile device and select your desired difficulty level: Easy, Medium, Hard, or Expert.

2. Once the game board loads, observe the 9x9 grid divided into nine 3x3 subgrids. Your goal is to fill every empty cell with the correct number.

3. Tap on an empty square to select it. A number pad will appear at the bottom of the screen.

4. Tap the number you believe fits in the selected square. Remember, each number from 1 to 9 must appear exactly once in every row, column, and 3x3 subgrid.

5. Use logic and elimination strategies to determine the correct numbers. Avoid guessing, as it may lead to mistakes.

6. If you're unsure about a number, activate pencil mode to write down possible candidates in a cell without committing to a final answer.

7. Use the hint button if you're stuck and need assistance. It will reveal a correct number for one square.

8. Continue filling in numbers and checking your progress until the entire grid is completed correctly.

9. When the board is filled without any errors, the level is completed and you can move on to a new challenge.

10. Play regularly to improve your memory and logical thinking with each puzzle.