Game theory is an autonomous discipline that is used in applied mathematics, social sciences, most considerably in economics, as well as in biology, engineering, political science, international relations, computer science and philosophy. Game theory is the mathematical study of strategy and conflict, in which an agent’s success in making choices depends on the choice of others. It was initially developed in economics to understand a large collection of economic behaviors, including behaviors of firms, markets and consumers. Game theory has been used to attempt to develop theories of ethical or normative behavior as well. In economics and philosophy, scholars have applied game theory to help in the understanding of rational behavior. The purpose of this paper is to clarify the following issues: firstly, to provide very brief overview of game and game theory; secondly, to discuss background and impact of game theory; thirdly, to analyze the prisoner’s dilemma game and finally, to present applications of game theory with special attention to philosophy.