You have to be more specific. Game theory is a means rather than an ends in itself. Most political scientists use game theory to study some substantive topic (e.g. legislative bargaining in American politics or nuclear proliferation in International Relations) rather than studying game theory just for the sake of doing game theory. If you are interested in the latter then an Economics Phd would be more appropriate.
Also, political methodology as a field and game theory are two different things. The former refers to statistical analysis of political data while the latter falls under the umbrella of 'formal theory/modelling'.