First there was Natural Philosophy, the knowledge of how the world worked before math became involved. Next it grew into the Philosophy of Geometry, when the math allowed the Philosophers of different peoples and cultures create metrics by which to measure the world. The discipline of Physics came next, and people were able to measure, reflect and predict the motions of their surroundings. Around the same time General Science and Mathematics, began to branch off from the tree of philosophy.
In what is considered the modern era, we have several philosophers tackling people and their behavior, attempting to get it all down to a science where there is a level of certainty and predictability. In the development of the economic discipline we have great altruists and philosophers who tried to sum up the behavior of men.
When physics and its ability to predict accurately came around and explain became more a consistent way how the world works, great economists began working towards that same level of truth. Alfred Marshal, comes along and makes economics explanatory and usable through math. He creates the interactive formula of supply and demand that we can apply to behavior and not just buying habits.
Decades later, Game Theory emerged, as the mathematical tools of economics became more sophisticated. Enter the 2 grand fathers of games as we know them: HG wells and John Von Neumann. Both brought gaming, beyond their previous boundaries. HG wells, as any war gamer and RPgamer made games and design to the masses. John Von Neumann furthered Game Theory, ambitiously attempting to give it physics-like utility.
Game Theory is the science of structured interactions and the complex patterns that emerge from them. It slowly gaining momentum as it is used in developing more efficient and fair methods of interaction, especially in State Policies, Biology (Medicine), Business, and War. The same principles can be found in game design, as hobbyists try to make their setting and game more challenging, sustainable, and fun.
We gamers, typically GMs, work on Game Design to build a better game. In my experience, we address challenges in making behavior, fairness, sometimes Ethics, stimulus and problem solving work in the way we see the world. Game Design is a way to simply and communicate the complex ideas of how the world ought to, should, can be from the GM's perspective.
One can say that he can learn about the entire personal philosophy of a Game Designer from the way he makes his games or tweaks a game system. The values and expectations he plays on humans or sentient beings can be seen in their treatment. How the GD approaches Social Status, Fate, Luck and hard work. To those who grew up on RPGs, Game Design is a language to discuss and relate these ideas and to test, share and express them with others and their unpredictable reactions.
The language of Game Design, is the language of everyman trying to make sense of his perspective and let others see the world in his point of view.