The form best embedded in the homo sapiens’ conscious is the prisoner dilemma which considers the problem that two actors have incentive to defect (confess in order to gain reduced sentence). Moral issues aside, game theory is a mathematical analysis that investigates how to reach an optimal outcome.
Where calculus has as one primary application the finding of (local) maxima and minima Game Theory can be understood as another optimization problem but expressed commonly from a selfish point of view. To rephrase where calculus concerns abstract data that can but not necessarily reflects individual agents, Game Theory does emphasize rewards of individual actors.
The nash equilibrium in this bounded universe expresses the state of outcomes in which none of the actors can improve without depression of one of the other actors.
Another interesting configuration is the case where actors reach a suboptimal outcome (with regards to the interests of both actors) because of the absence of absolute information.