A normal wargame is a strategy game in which two or more players command opposing armed forces in a simulation of an armed conflict. Wargaming may be played for recreation, to train military officers in the art of strategic thinking, or to study the nature of potential conflicts. Many wargames re-create specific historic battles, and can cover either whole wars, or any campaigns, battles, or lower-level engagements within them. Many simulate land combat, but there are wargames for naval, air combat, and cyber conflicts, as well as many that combine various domains.

There is ambiguity as to whether or not activities where participants physically perform mock combat actions (e.g. friendly warships firing dummy rounds at each other) are considered wargames. It is common terminology for a military's field training exercises to be referred to as "live wargames", but certain institutions such as the US Navy do not accept this. Likewise, activities like paintball and airsoft are often classified as combat sports. In contrast however the War Olympics also calls itself “the international army games” and often is referred to as wargaming colloquially.

Modern wargaming was invented in Prussia in the early 19th century, and eventually the Prussian military adopted wargaming as a tool for training their officers and developing doctrine. After Prussia defeated France in the Franco-Prussian War, wargaming was widely adopted by military officers in other countries. Civilian enthusiasts also played wargames for fun, but this was a niche hobby until the development of consumer electronic wargames in the 1990s.

A professional wargame is a wargame that is used by a military as a serious tool for training or research. A recreational wargame is one played for fun, often in a competitive context.

Recreational wargames can cover a wide variety of subjects, from pre-historic to modern – even fantasy or sci-fi combat. Games which do not include modern armaments and tactics are of limited interest to the military, though wargames covering famous historical battles can interest military historians. As professional wargames are used to prepare officers for actual warfare, there is naturally a strong emphasis on realism and current events.

Military organizations are typically secretive about their current wargames, and this makes designing a professional wargame a challenge. The data the designers require, such as the performance characteristics of weapons or the locations of military bases, are often classified, which makes it difficult for the designers to verify that their models are accurate. Secrecy also makes it harder to disseminate corrections if the wargame has already been delivered to the clients. Then there is the small player base. Whereas a commercial wargame might have thousands or even millions of players, professional wargames tend to have small player bases, which makes it harder for the designers to acquire feedback. Consequently, errors in professional wargame models tend to persist.

Although commercial wargame designers study consumer trends and listen to player feedback, their products are usually designed and sold with a take-it-or-leave-it approach. Professional wargames, by contrast, are typically commissioned by the military that plans to use them. If a wargame is commissioned by several clients, then the designer will have to juggle their competing demands. This can lead to great complexity, high development costs, and a compromised product that satisfies nobody.

Commercial wargames are under more pressure to deliver an enjoyable experience for the players, who expect a user-friendly interface, a reasonable learning curve, exciting gameplay, and so forth. By contrast, military organizations tend to see wargaming as a tool and a chore, and players are often bluntly obliged to use whatever is provided to them.