Some time ago I built a small robotic car that aimed to be reactive (despite not being remote controlled). The car uses a line-following mechanism based on light reflection, achieved through an LED and a light detector. Additionally, I integrated an ultrasonic sensor to detect obstacles, enabling the car to stop or change direction in response to its surroundings. So despite the fact that the car doesn't use a remote, it reacts in real time to environmental changes by continuously processing sensor input and adjusting its movement accordingly. Programming was done using the Arduino runtime, which provides helpful libraries, standardized naming conventions, and a large online support community. While Arduino abstracts some low-level details, this project still required careful work with both digital and analog I/O, interpreting sensor data, and controlling motors in real-time. One of the important challenges was tuning the system. Finding the right thresholds, delays, and behaviors through calibration and field testing to make the car actually drive as expected. It was a good experience for getting into embedded debugging, real-world sensor behavior, and system responsiveness.