Robotics is a great and fun way to challenge yourself to learn more skills including coding, circuits, design challenges. The Lego Mindstorms EV3 system is great for tackling design challenges with a wide range of sensors and motors, lego, and other materials like cardboard and duct tape. Arduino is another more advanced option.
Finally, you can also use code.org to develop a robot controller app to drive wireless robots remotely and compete with others!