economics, research, and diplomacy. The time span of the game is in the order of months or years. Examples Flames of War is a tactical-level historical miniature wargame that simulates land battles during World War 2. TACSPIEL is an operational-level professional wargame developed in the 1960s by the US Army for research into guerilla warfare. The Sigma war games were a series of strategic-level professional wargames that sought to predict the outcome of the Vietnam War. Hearts of Iron IV is a strategic-level computer wargame set in the mid-20th century. Wings of War is tactical-level recreational wargame that simulates World War 1 aerial dogfights. Star Wars: X-Wing is a fantasy wargame whose rules are based on Wings of War. Design issues Realism A wargame must simulate warfare to a reasonable degree of realism, though what counts as sufficient realism depends on the players. Military wargames need to be highly realistic because their purpose is to prepare officers for real warfare. Recreational wargames only need to be as realistic as it pleases the players, so in most recreational wargames the emphasis is on verisimilitude, i.e. the satisfactory appearance of realism. In any case, no wargame can be perfectly realistic. A wargame's design must make trade-offs between realism, playability, and fun, and function within the constraints of its medium. Fantasy wargames arguably stretch the definition of wargaming by representing fictional or anachronistic armaments, but they may still be called wargames if they resemble real warfare to the satisfaction of the players. For example, Warhammer Fantasy Battle has wizards and dragons, but the bulk of the armaments are taken from medieval warfare (spearmen, knights, archers, etc.). Validation is the process by which a given wargame is proven to be realistic. For historical wargames, this usually means being able to accurately recreate a certain historical battle. Validating military wargames is sometimes tricky as they are typically used to simulate hypothetical future scenarios. Complexity Whereas the rules of Chess are relatively simple, and those of Go even simpler, with the complexity of these games an emergent property of the evolving strategic state of the board, wargames contrarily tend to have very sophisticated rules as a matter of their commitment to representing the concrete realities of (various kinds of) warfare. Generally speaking, the more realistic a wargame seeks to be, the more complicated its rules are. For example, chess pieces only have a few rules determining