Game theory is a concept related to representing strategic situations mathematically. Chess, for example, is commonly used as an analogy for a range of situations, and gaming, particularly computer gaming, applies these situations in a mathematical context. The uses of game theory are endless, for modeling situations, behavioral trends, marketing, advertising, statistical analyses, etc. Studies include simulations, trying to quantify possible actions, behaviors, and is particularly useful in player analyses. Sport professionals often use a method of game analysis which is very similar to game theory. 
Examples of Game Theory:
Practical: The Sims, Civilization, chess, Go, World of Warcraft http://levine.sscnet.ucla.edu/general/whatis.htm http://plato.stanford.edu/entries/gametheory/ http://simple.wikipedia.org/wiki/Game_theory 
World of warcraft. 
Chess. 
