FUNDAMENTALS OF GAME DESIGN, SECOND EDITION
Gameplay
The challenges in a CMS are largely economic. The player must understand how the internal economy of the game works and how to manipulate it to produce economic growth. Growth provides the resources required for the construction that is usually the overall goal of the game. The game's actions consist of activities that stimulate growth and ways of using the resources that the player earns.
The majority of CMSs are games of indirect control. The game simulates a process that the player can alter only in limited ways, and the player learns by trial and error how the changes that he makes affect the functioning of the process. The game may offer simulated people (see the section "Simulating Individuals" later in this chapter), but they are usually autonomous. Their behavior model governs what they do, and while they respond to stimuli, the player can't give them direct orders.
In contrast, a war game is a game of direct control. The player tells his troops exactly where to go and what to do, and the troops do it. The simulated soldiers demonstrate little or no autonomous behavior. If the player tells them to stand and wait someplace, they wait there forever.
However, the dividing line between direct and indirect control is a fuzzy one. Certain player activities, such as choosing where to build something, constitute direct control of the game. Others, such as trying to boost sales by reducing prices, are classed as indirect control. Reducing prices is a direct action with respect to the prices themselves, but not with respect to sales; the (hoped for) consequent rise in sales is the result of the player's indirect control of the game.
In most CMSs, construction itself is not challenging: The player clicks the mouse on a location, and something appears there. The challenge is in obtaining the resources needed for the construction. Construction lets the player exercise her imagination and create something unique and personal. Accordingly, you, as the designer, need to find a way to make the user interface for construction easy and enjoyable to use.
Construction mechanisms in CMSs tend to be of two types: purchase-and-place or plan-and-build. Games in which construction is the primary activity tend to use the purchase-and-place mechanism; games in which the player alternates between construction and management modes are more likely to use the plan-and-build mechanism.
In the purchase-and-place construction mechanism, when the player buys an object (a segment of wall, say), the game deducts the resources to build that object from stockpiles, and the object immediately appears in a designated location. This lets the player build rapidly, adding pieces like using LEGO blocks. You should use this mechanism if construction is the primary activity in your game. The activity needs to be easy and continuous, not something the player has to wait for. This is how SimCity works: Zoning property and constructing civic amenities such as police stations and airports happens instantly because zoning and constructing are the primary activities in the game.
The plan-and-build mechanism is more often seen in games in which the player does a little construction, then some management, then more construction, and so on. In plan-and-build, the player marks out an area in which new construction will appear. The game sometimes displays the new building in a ghostly, semitransparent form to indicate that it is under construction. However, construction takes time. If the game includes simulated people, you might be able to see them at work on the building; if those people stop work, the building might be left in a partially completed state. You will find plan-and-build in strategy-CMS hybrids where the player may be under threat of invasion and time is of the essence.
In plan-and-build, you don't have to remove all the required resources from storage at once because the construction takes place over time. In the Settlers series, wood and stone have to be transported a little at a time from stockpiles to the construction site. This puts an extra burden on the player to manage his resource flow but also gives him more control. In contrast, the Age of Empires series uses
plan-and-build but deducts the resources necessary for construction immediately when it is planned. Resources drain out of the game instead of being transported to the site. Although this is unrealistic, it means that the player can build something only after he definitely has enough resources for it, and he doesn't have to worry about moving resources from point to point.
Dungeon Keeper, another hybrid, makes a particularly interesting example because construction is actually excavation; it takes place underground, and the player can't see the area he is digging into. Excavations often encounter immovable rock or lead to previously unknown caves, underground rivers, or pools of lava. Excavation is also irreversible; the game offers no way to close an excavated area. This encourages players to be cautious. Suddenly digging an opening into an area full of enemy creatures is a major hazard of the game.
