Game design is a creative process that involves imagining and defining how a game will work, including its story, rules, and elements. A game designer performs tasks like conceptualizing the game, designing its functionality and aesthetics, and communicating the design to a team. Game design incorporates both artistic and scientific principles - the conceptualization of ideas and aesthetics involve creative arts, while ensuring the game functions well may require principles from science and math. An effective game design balances elements like core mechanics, storytelling, and interactivity, and is documented in a design document to guide development.