FUNDAMENTALS OF GAME DESIGN, SECOND EDITION
ABSTRACTING THE DISTRIBUTION PROCESS
To reduce these problems—yet still require the players to create the resources that units need—you can make the production process concrete, but abstract the distribution process. For example, the troops in Warcraft eat food. The food is produced on farms (which may be destroyed by the enemy, thereby reducing production), but once the food is produced, it is magically available to all the player's troops everywhere. The existence of the troops causes the food to disappear from storage, but the food doesn't actually have to be transported to where the troops can eat it.
This decentralization of resources can permit unrealistic strategies if you do not handle it carefully. In Age of Empires, for instance, a player can send a lone peasant into a remote area to build a barracks, which has the function of creating troops. Assuming that it is not spotted by the enemy, the barracks immediately starts producing troops right on the enemy doorstep with no regard for supply lines or resource distribution. Although this is an imaginative way to exploit the decentral - ized-resources mechanic, it harms the players' suspension of disbelief because it's so unrealistic.
In his regular design column for U. K.-based Develop magazine, Dave Morris suggested another alternative that rewards a player for maintaining supply lines without actually requiring her to personally manage the transportation of materiel
(Morris, 2001). Morris was the lead designer on Warrior Kings, and for that game he proposed a special unit called the supply wagon. Supply wagons carried food, and so long as troops were near a loaded supply wagon, they regained health points (which consumed the food). When the food in the wagon ran out, the supply wagon automatically trundled back to the nearest friendly palace (palaces acted as storehouses) for more food. Units whose supply wagon couldn't get back to a source of supplies couldn't regain health. This rewards the player for keeping supply lines open but does not actually require her to do so. (Unfortunately this idea was not implemented in the final version of the game for lack of time.)
Another way to abstract the distribution of supplies while still requiring the player to pay some attention to them is to let the player build roads. Consider the territory map in Figure 14.4.
B
A
C
Town B has access to a forest—it has a road (supply line) leading directly to the forest, providing a ready source of lumber. This allows Town B to build wood-based units, such as catapults. Town A is linked to Town B via a road. This road provides a readily available supply route between Town A and Town B. Hence, Town A has exactly the same production capabilities as Town B. Anything that is available to Town A is also available to Town B, and vice versa. Town C is a newly built town.
No roads have been built to Town C, so it does not have access to the resources of Towns A and B until a linking road is built.
This is the approach taken by Civilization III. Of course, it's still not an entirely accurate solution—materials are assumed to travel instantaneously along the roads. (It's interesting to note, though, that previous iterations of the Civilization series did implement trade caravans, but Civilization III removed that feature to improve gameplay.)
Two out of the three races in StarCraft use an influence map to indicate where their influence has spread (although the core mechanics use these maps only to determine where structures may be constructed and not to provide supplies to mobile units). For example, the Protoss power beacons, which provide power to the Protoss factories, have a limited radius of power distribution. When the player wants to construct a new factory, the game displays the influence map by color-shading the landscape, showing the areas where the factory may be built.
