A wargame is a strategy game in which two or more players command opposing armed forces in a realistic 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 recreate 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 and air combat as well.

Generally, activities where the participants actually perform mock combat actions (e.g. friendly warships firing dummy rounds at each other) are not considered wargames. Some writers may refer to a military's field training exercises as "live wargames", but certain institutions such as the US Navy do not accept this. Likewise, activities like paintball are sports rather than wargames. Wargames are a mental activity.

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.