It happens to be a fact that other parts of Game Theory, such as those studied by Nash, find more real world applications. The real world is full of the complications absent from classic games like chess (and dealt with by combinatorial game theory).=:
- more than two players
- imperfect information
- non-sequential actions
and others that don't immediately spring to mind.
It shouldn't be beyond the capabilities of @Optimissed to understand that the only part of the broad subject of Game Theory that is relevant to chess is Combinatorial Game Theory. While the other parts involve rigorous analysis of abstractions (in the way I referred to earlier), combinatorial game theory is intuitively simpler to comprehend.