An ImpactJS developer is responsible for creating interactive and dynamic web games using the ImpactJS JavaScript engine. They write, test, and debug code, ensuring the game runs smoothly across various platforms. They also design game elements, integrate visual and audio components, and optimize game performance for mobile devices. They work closely with graphic designers and other developers to create a seamless and engaging user experience. Additionally, they might be involved in updating existing games, fixing bugs, and implementing new features based on user feedback. They need strong problem-solving skills, creativity, and a good understanding of game mechanics.