This core topic addresses the fundamental ideas behind the design of electronic games as virtual environments. It touches on relevant formal fields such as systems theory, cybernetics, and game theory. Included are basics of interactive design, including interface design, information design and human-computer interaction. Emphasis is placed on how virtual game environments function to create experiences, including rule design, play mechanics, game balancing, social game interaction and the integration of visual, audio, tactile and textual elements into the total virtual game environment experience. Game documentation and play-testing are also covered.