1. Launch Trains.io 3D on your mobile device to begin playing.

2. Control your train by dragging your finger across the screen to steer it in different directions.

3. Navigate through the 3D world and collect screws scattered across the map to grow your train in length.

4. Look out for toolboxes, which give you extra growth and help you become larger faster.

5. Avoid crashing into other trains or obstacles, as this will end your game.

6. Defeat other trains by maneuvering your train so they crash into your body, allowing you to absorb their parts and grow even longer.

7. Double tap the screen to activate a speed boost, helping you escape danger or catch opponents. Use boosts wisely as they consume collected items.

8. The longer your train grows, the higher your score. Aim to become the biggest train on the leaderboard.

9. Stay alert and use strategy to trap smaller trains and avoid being trapped by larger ones.

10. Keep collecting items and defeating opponents to dominate the map and become the grand train.

11. Practice to improve your reflexes and control, and challenge yourself to beat your high score with every play.

12. Enjoy the gameplay and good luck becoming the ultimate train in Trains.io 3D.