wargame (also war game) is a strategy game that deals with military operations of various types, real or fictional. Wargaming is the hobby dedicated to the play of such games. When used by the military to study warfare, “war game” may refer to a simple theoretical study or a full-scale military exercise. Hobby wargamers have traditionally used “wargame”, while the military has generally used “war game”; this is not a hard and fast rule. Although there may be disagreements as to whether a particular game qualifies as a wargame or not, a general consensus exists that all such games must explore and represent some feature or aspect of human behaviour directly bearing on the conduct of war, even if the game subject itself does not concern organized violent conflict or warfare. Wargames are generally categorized as historicalfantasy, or science fiction.

Extract from Wikipedia:

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