game theory is more a state of mind than a specific strategy. you would be using some aspect of it all the time to think about the optimal and rational moves of your counterparty or the of your competition.
I was a teaching assistant for a grad level game theory class in college.
it’s more generally about determining the outcome if everyone behaves optimally. The generalized skill is to think about the other guys’ incentives, information, utility function and understand their likely and rational course of action.