A wargame 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, which can also be called conflict simulations, or consims for short. When used professionally to study warfare, it is generally known as a military exercise or war game. Note that hobby wargamers have traditionally run the two words together, but the military has generally kept them separate; it is not a hard and fast rule, however. 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 illuminate or simulate 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. The business wargames exists too, but in general they are only role playing games based on market situations.

Wargames are generally categorized as historical, hypothetical, fantasy, or science fiction. Historical games by far form the largest group. These games are based upon real events and attempt to represent a reasonable approximation of the actual forces, terrain, and other material factors faced by the actual participants. Hypothetical games are games grounded in historical fact but concern battles or conflicts that did not (or have yet to) actually happen. Fantasy and science fiction wargames either draw their inspiration from works of fiction or provide their own imaginary setting. Highly stylized conflict games such as chess are not generally considered wargames, although they are recognized as being related. Games involving conflict in other arenas than the battlefield, such as business, sports or natural environment are similarly usually excluded.