Wargame
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 their behaviour, such as how and when they are allowed to move or capture based on their type and board location, providing a highly abstracted model of warfare which represents troop composition and positioning. Stones in Go have no properties, behaviours, or state on their own, and only potentially represent, relative to other stones, elements of a larger board position, providing an extremely abstract strategic model in which the determinant of victory is a generalisation of territorial control and influence projection. Contrarily, in wargames counters typically represent decidedly more concrete and internally quite complex entities (companies, battalions, etc.), with detailed interior state (stat blocks and tables of troop numbers, equipment, operational readiness, artillery charts, etc.), often with convoluted rules governing how they operate and interact, and furthermore the global state of the game is often governed by extensive non-local rules representing exigencies like seasonal weather or supply lines.
This makes wargames difficult to learn, as it can be difficult to simply begin playing without already understanding a great deal about how to do so. Even experienced wargamers usually play with their rulebook on hand, because the rules for most wargames are too complex to fully memorize. For many people, the complexity also makes wargames difficult to enjoy, but some players enjoy high realism, so finding a balance between realism and simplicity is tricky when it comes to recreational wargames.
One way to solve the problem of complexity is to use a referee who has the discretion to arbitrate events, using whatever tools and knowledge they deem fit. This solution is popular with military instructors because it allows them to apply their own expertise when they use wargames to instruct students. The drawback of this approach is that the referee must be very knowledgeable in warfare and impartial, else they may issue unrealistic or unfair rulings.
Another way to address complexity is to use a computer to automate some or all of the routine procedures. Video games can be both sophisticated and easy to learn, which is why computer wargames are more popular than tabletop wargames.

Scale: Every wargame must have a sense of scale, so that it may realistically simulate how topography, distance, and time affect warfare. Scale is usually expressed as a ratio, e.g. a scale of 1:1000 indicates that 1 cm on the game map represents 10 m (1,000 cm). In miniature wargaming, scale is more often expressed as the height of a model of a human measured from the base of its feet up to the eyes or top of the head (e.g. 28mm).
Military wargames typically aim to model time and space as realistically as is feasible, so everything in the simulation conforms to a single scale. Recreational wargame designers, by contrast, tend to use abstract scaling techniques to make their wargames easier to learn and play. Tabletop miniature wargames, for instance, cannot realistically model the range of modern firearms, because miniature wargaming models are typically built to a scale between 1:64 and 1:120. At those scales, riflemen should be able to shoot each other from several meters away, which is longer than most game tables. If model soldiers could shoot each other from opposite ends of the table, without the need to maneuver, the game would be very monotonous. For example, the miniature wargame Bolt Action solves this problem by reducing a rifle's range to 24 inches, a sub-machine gun's range to 12 inches, and a pistol's range to 6 inches. Even if these ranges are not realistic, their proportions make intuitive sense (a rifle's range is longer than a sub-machine gun, due to the differing ammunitions) and thus preserve some verisimilitude, all the while compressing the battle to fit the confines of the table. Additionally, the ranges are multiples of 6, which makes them easier to remember.

Fog of war: In real warfare, commanders have incomplete information about their enemy and the battlespace. A wargame that conceals some information from the player is called a closed game. An open wargame has no secret information. Most recreational wargames are open wargames. A closed wargame can simulate the espionage and reconnaissance aspects of war.
Military wargames often use referees to manage secret information. The players may be forced to sit in separate rooms, and communicate their orders with the referee in the game room, who in turn reports back only the information he judges the players should know. Some recreational wargames use a referee too, often referring to them as "the GameMaster" (e.g. Warhammer 40,000: Rogue Trader).
The fog of war is easy to simulate in a computer wargame, as a virtual environment is free of the physical constraints of a tabletop game. The computer itself can serve as the referee.

Types: 

Miniature: Miniature wargaming is a form of wargaming where units on the battlefield are represented by miniature models, as opposed to abstract pieces such as wooden blocks or plastic counters. Likewise, the battlefield itself is represented by model terrain, as opposed to a flat board or map; naval wargames are often played on a floor because they tend to require more space than a tabletop. Most miniature wargaming is recreational because issues of scale get in the way of realism.
Miniature wargaming can be more expensive and time-consuming than other forms of wargaming. Furthermore, most manufacturers do not sell ready-to-play models, they sell boxes of model parts, which the players are expected to assemble and paint themselves. This requires skill, time, and money, but many players like the opportunity to show off their artistic skills. Miniature wargaming is often as much about artistry as it is about play.

Board: A board wargame is played on a board that has a more-or-less fixed layout and is supplied by the game's manufacturer. This is in contrast to customizable playing fields made with modular components, such as in miniature wargaming.

Block: In block wargaming, the Fog of War is built into the game by representing units with upright wooden blocks that are marked on only one face, which is oriented towards the player who owns the block. The opponent cannot see the markings from his position. The first such block wargame was Quebec 1759 by Columbia Games (previously named Gamma Two Games), depicting the campaign surrounding the Battle of the Plains of Abraham.

Card: Because of their nature, cards are well suited for abstract games, as opposed to the simulation aspects of wargames. Traditional card games are not considered wargames even when nominally about the same subject (such as the game War).
An early card wargame was Nuclear War, a 'tongue-in-cheek game of the end of the world', first published in 1966 and still published today by Flying Buffalo. It does not simulate how any actual nuclear exchange would happen, but it is still structured unlike most card games because of the way it deals with its subject.
In the late 1970s Battleline Publications (a board wargame company) produced two card games, Naval War and Armor Supremacy. The first was fairly popular in wargaming circles, and is a light system of naval combat, though again not depicting any 'real' situation (players may operate ships from opposing navies side-by-side). Armor Supremacy was not as successful, but is a look at the constant design and development of new types of tanks during World War II.
The most successful card wargame (as a card game and as a wargame) would almost certainly be Up Front, a card game about tactical combat in World War II published by Avalon Hill in 1983. The abstractness is harnessed in the game by having the deck produce random terrain, and chances to fire, and the like, simulating uncertainty as to the local conditions (nature of the terrain, etc.).
Dan Verssen Games is a specialist designer and publisher of card games for several genres, including air combat and World War II and modern land combat.
Also, card driven games (CDGs), first introduced in 1993, use a deck of (custom) cards to drive most elements of the game, such as unit movement (activation) and random events. These are, however, distinctly board games, the deck is merely one of the most important elements of the game.

Computer: The term "wargame" is rarely used in the video gaming hobby; the term "strategy game" is preferred. "Computer wargame" distinguishes a game from a "tabletop wargame".