A Game Prototyping Developer conceptualizes, designs, and creates prototypes for video games. They test gameplay ideas, game mechanics, storylines, and character concepts in a simplified version before full development. By using their programming skills, they build interactive mock-ups to evaluate the feasibility and fun factor of the game. They work closely with game designers and developers, adjusting and refining the prototype based on feedback and play-testing results. Their work is critical in the early stages of game development, helping to identify potential issues and improvements, thus saving time, effort, and resources in the overall development process.