[profquail]

One of the most basic 'games' in game theory is called the Prisoner's Dilemma:

http://en.wikipedia.org/wiki/Prisoner%27s_dilemma

Basically, the idea here is to figure out your best strategy for the 'game' (which really means any situation where you need to make a decision), given that the other "players" don't cooperate with you in any way (i.e. you assume they are going to act in their own self-interest).

The most basic successful strategy for the Prisoner's Dilemma is called "Tit-for-Tat", in which you always choose the "altruistic" option, unless the other player chose against you last time.

http://en.wikipedia.org/wiki/Tit_for_tat