The Field of Battle
In addition to characteristics of the units and the rules for their interaction, the design of the field of play presents its own challenges. A historical wargame has to function as both a playable game and an accurate simulation of history, two concerns that can often be at odds with each other. Wargame designer James Dunnigan writes about some of the design concerns in creating a game map: There are two primary things to keep in mind when examining a geographical game map. First, it often has a grid, most often a hexagonal grid, superimposed over it…. The second point is that in most historical situations, only very large ("gross") terrain features have any significant effect on operations.Thus, a great deal of detail on a map will often get in the way of providing an accurate simulation. The designer usually feels obliged to justify all of this detail. Often the gamer will be equally expectant that all of this detail be put to some use or otherwise why bother him with it. There is an unspoken assumption that only that which is essential is displayed. It is normally considered a bad design if information is included in the game that does not contribute to one's understanding of what is going on. [9]
The real world is infinitely rich, and cartographers—including game map-makers—are faced with the representational challenge of simplifying geography in a way that is meaningful for the intended use of the map. In a map for a historical wargame, designers must decide what to include and what to leave out, how to abstract and structure the information to fit in the larger game system. As Dunnigan puts it, too much detail in the terrain can get in the way of a player's understanding; only "gross" terrain features have a real impact on military operations. Abstraction emphasizes the features critical to understanding the terrain, while minimizing the "noise" created by less important elements. The grid of the map is one important consideration. Units in a grid-based wargame move only within the hexagons or squares superimposed on the map. Because of this, there is a very specific relationship between the grid and the terrain. The game designer not only needs to select the relevant terrain features, but also decides how those features fit into the grid. Because terrain can affect movement, simply laying a grid over topographically correct terrain creates formal ambiguity. For example, in a particular game, units might not be able to cross rivers. If a river flows through the middle of a map hex, does it mean that players can enter the hex but not exit out the other side, or that they cannot enter the hex in the first place? A common solution in wargame map design is to stylize the shape of rivers so that they are located only on the edges of hexes. This solution makes the movement-blocking role of rivers in the game completely clear. Designing the terrain to accommodate the game grid lessens the geographic accuracy of the map: there are no naturally occurring rivers that can be plotted exactly along a hexagonal grid. But for game design purposes, abstraction that eliminates formal ambiguity is essential.

geographically accurate river
Questions about rivers and wargame map design do not end there. If one purpose of a historical wargame is fidelity to the real battlefield, which rivers should be included? When does a tributary or stream become too small to be indicated on the map? Which rivers should have an impact on the play of the game? As Dunnigan points out, if something is prominent on the map, a player will expect it to impact game play: a visible feature that does not contribute to the functioning of the rules is bad design. In designing a wargame map, in deciding which features to include and how to represent them within the larger simulation, you are doing more than just creating a map. You are constructing a space of meaning. If your game simulates combat between individual soldiers, the terrain elements you include make a representational statement about which type of terrain affects a certain kind of combat. The meaning of a wargame map arises not just from its geographic or pictorial features: the meaning derives from the role the map plays in the larger game experience. The formal qualities of the map make certain player actions possible, actions that constitute the ongoing moments of game play.
Not all wargames use a grid. Some miniatures games measure unit movement in inches, and in some digital wargames, unit movement is free-form and highly granular. In these cases, the principles of abstraction and meaningful play still hold. Are the map elements communicating their meaning to the player? Do they affect game play in ways that make sense within the experience of the game emerges. In this way, the play of simu-lation brings us back to the most fundamental questions of game design.

hexagonally stylized river
[9]James F. Dunnigan, Wargames Handbook, Third Edition: How to Play and Design Commercial and Professional Wargames (San Jose: Writers Club Press, 2000), p. 109.