A jMonkeyEngine developer designs and implements game applications using the jMonkeyEngine game development suite. They create interactive, real-time environments, characters, and animations, and integrate physics, sound, and user input. They also handle debugging and testing, ensuring performance optimization and smooth user experience. Moreover, they work on adapting the engine to suit specific project requirements, which might include creating custom shaders or extending the engine's functionality. They often work closely with game designers, artists, and other developers, contributing to the entire game development lifecycle. They must be proficient in Java and have strong understanding of graphics principles.