Game Features

CSGs let the player construct and manage some organized system that he can build up from constituent parts—a city, a building, an anthill, or whatever the game permits him to design. Most CSGs offer two sets of tools: one set for building and one set for managing and (normally) growing an internal economy. Building is generally considered easy, but managing can be tricky indeed.

The Player’s Role

When designing any game, the first question you have to ask yourself is: What is the player going to do? Usually the answer to this question takes the form of a clear statement of the player’s role in a game: pilot, detective, irradiated hedgehog, and so on. In a CSG, however, it’s not as easy to define the player’s role because that role seldom corresponds to an actual activity in real life. The mayor of a city doesn’t really lay out its streets or make zoning decisions personally. So instead of thinking about the role in a literal sense, think of it as a collection of challenges, actions, and opportunities.

A CSG appeals to the player because he gets to make something of his own. Working carefully, tending and tweaking, he can build a tiny settlement on the banks of the Tiber and turn it into the glorious city that was Rome. Not the original Rome or the game designer’s Rome but the player’s Rome—Rome as it would have been if the player had been in command. The desire to create is in the heart of all CSG players. To design a good construction and simulation game, understand that desire.

Progression

Unlike many other genres, CSGs don’t always include a story or progression from level to level. Games such as SimCity offer a set of scenarios for the player to play in, with varying degrees of difficulty, but one scenario doesn’t necessarily have any relationship to the previous or next one. However, this is not universal; Tiny Tower, a popular business simulation for mobile phones, allows the player to build a tower floor by floor.

Because many CSGs don’t impose a victory condition, there’s little sense of progress toward an end (although there is a sense of progress from the beginning). In fact, many CSGs don’t necessarily end at all. As long as the player avoids the loss condition (for instance, bankruptcy), the game can go on forever.

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SimCity, the Archetype CSG

Although it isn’t the oldest CSG, SimCity inspired all the CSGs that came after it for many years. Published by Maxis (now a part of Electronic Arts) originally for the Commodore 64, SimCity achieved its greatest success on the IBM PC, and the franchise continues today. A host of other games in the same mold followed—SimAnt, SimTower, SimFarm, and so on—which met with varying degrees of success. We’ll take a closer look at SimCity because it is such a prototypical example of the genre.

The object of SimCity is to build a city and attract people (called sims) to live and work there. The basic economic unit is money, which the player can spend in various ways to improve the city. The player’s primary task is to zone tracts of land into one of three types: residential, commercial, or industrial. As people move into the city, their occupation of these areas begins to produce tax revenue, thereby replenishing the city’s coffers. This produces a straightforward positive feedback loop: Zoning costs money, but occupied zones produce more money, thereby enabling the player to do more zoning.

The positive feedback is kept in check by other demands on the city’s purse. Sims will not move into a region simply because it has been zoned; it needs other amenities as well. Foremost among these is electricity, so the player has to buy power plants and electrical lines to provide it. The sims also need a way to travel from the residential zones to the industrial zones to work and to the commercial zones to shop. This requires road and rail networks, which also cost money. If the roads are inadequate to meet the traffic or if the sims have to travel too far to work, they will begin to move out of the city, resulting in a loss of tax revenue. Finally, when the city reaches certain population thresholds, the sims begin to demand expensive amenities: a sports stadium, an airport, and so on. Again, if the player doesn’t provide these, the sims begin to leave.

In addition to the electricity, roads, and civic amenities, the player pays for other common services, such as fire protection and police. Fires break out from time to time; left unchecked, they destroy the buildings and leave the land unzoned. To combat this, the player must build and maintain fire stations. Crime takes place in industrial areas, depressing property values and reducing tax revenues. Building police stations, at yet more cost, suppresses crime. Industrial areas and roads also cause air pollution, which further depresses the value of nearby residential property. The player cannot reduce air pollution; he simply has to keep industrial and residential areas separate.

The game’s algorithm mathematically determines the value of each area. A zoned area with parks or a river nearby will be worth more than a similar area that lacks these benefits. The more valuable a zone is, the more sims move in and the more tax revenues the zone produces. The player can build parks and situate residential zones near woods and rivers to increase their attractiveness.

The original SimCity, though now an old game, serves as an excellent model to study (see Figure 1). Because it was designed for low-performance machines, it couldn’t be too complex, so its internal economy is easy to understand.

Figure 1 The original SimCity

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Gameplay

The challenges in a CSG are largely economic, and often use currency as a specific resource in the game. 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.

Indirect Control

The majority of CSGs 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 e-book), but usually they are 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.

Construction

In most CSGs, 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 UI for construction easy and enjoyable to use.

Construction mechanisms in CSGs 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 appears immediately 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. Minecraft is also effectively a purchase-and-place game: Although the player doesn’t really “purchase” the blocks, she can place them instantly.

The plan-and-build mechanism is seen more often 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. Sometimes the game 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-CSG 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.

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Functional Construction Challenges

Construction and demolition is easy in most games: Point, click, and it happens, so long as the resources required are available. If you want to make the process more of a challenge, you can impose constraints on how things may be constructed and test to see whether the construction meets some required standard. The game Bridge It, for instance, requires its player to use certain predefined bridge elements—towers, beams, cables, and a roadway—to construct a bridge across a body of water. It also requires that the bridge actually support a load moving across it (see Figure 2). World of Goo, while purely a fantasy game, also uses its own unique laws of physics to challenge the player to construct something. See the section “Constrained Creative Play” in Chapter 9, “Creative and Expressive Play,” of Fundamentals of Game Design, Third Edition for more information about construction challenges.

Figure 2 Bridge It challenges the player to build a functional bridge. This one was a failure. (Image courtesy Chronic Logic and Auran.)

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You should consider whether you want demolition to cost something, cost nothing, or actually earn money. If it costs money to demolish something, you are, in effect, penalizing the player for changing her mind and perhaps encouraging her to plan more carefully in the future. She loses not only her initial construction cost for the item but the demolition costs as well. If demolition costs nothing, the player loses only her construction costs. (Minecraft doesn’t charge anything to disassemble an object.) If she actually gets something back, it’s usually called selling the item or structure rather than demolishing it, an arrangement that further reduces the price the player pays for changing her mind. If she can sell back a structure for exactly as much as she paid, there is no net cost at all for building a thing and destroying it later. CSGs rarely work this way because to do so removes some of the challenge of managing their resources.

Social Play

Because construction games involve a lot of creative play, players will want to be able to share and show off what they have made with friends and others. You can support this with screenshots (as in FarmVille), video (particularly popular in Minecraft, especially since Minecraft offers almost no tutorial help), being able to have friends visit and see their world (the Toy Box mode of Disney Infinity, or World of Zoo for the Nintendo DS), and online multiplayer designs (Minecraft again, or, for that matter, Second Life). The social rewards of constructing and building something really cool is as much a tangible reward as other in-game awards that were used in the past. If you let the players build something interesting and unique, be sure to think about how they will be able to show it off.

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Minecraft, a New Approach to CSGs

Without doubt, Minecraft has supplanted SimCity as the most famous CSG in the modern era, but it is distinctly different in many ways. Like most CSGs, it is a sandbox game that gives the player no explicit goal to aim for, and construction is the primary activity. Unlike them, however, it is an avatar-based game rather than using a multipresent interaction model, which means the player has to move to the location where he wants to build something (see Figure 3). Both first- and third-person camera models are available. The game has two play modes: survival mode, in which the player must look after his avatar’s health and safety (monsters come out at night), and creative mode, in which he is always safe and has unlimited resources. (Hardcore mode is really just a variant of survival mode.) Because of its survival element, Minecraft can also be classified as an action-adventure, but the strong emphasis on construction means that it’s a CSG-action hybrid at most.

Perhaps the most important difference between Minecraft and other CSGs is that the player does not have to manage an ongoing economy, with resources that are produced and consumed by automated processes. Instead, he mines resources by digging in the ground and combining them together to craft new resources. The game’s world is generated procedurally, and it is driven by vastly complex and powerful mechanics that produce emergent gameplay. One resource in the game, called redstone, can be used to make digital logic gates and to actually build simple computers and circuits within the game. Because Minecraft is easy to modify, there are many, many mods for the game. MinecraftEdu is an organization that promotes and assists using Minecraft in the classroom.

Figure 3 Minecraft

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Victory and Loss Conditions

A good many CSGs do not provide any victory condition; the player simply builds whatever she likes as effectively as she can within the constraints of the system. These games might well provide a loss condition, however. For example, total depletion of resources (or, in monetary terms, bankruptcy) is the loss condition in Monopoly. Victory in Monopoly consists simply of bankrupting all the other players; that is, forcing all the other players to meet the loss condition so that the last one left is declared the victor.

If you do want to define a victory condition, it’s best to do it in the context of a predefined scenario that you have created for the player rather than a free-form construction mode. Give the player a partially constructed city (or whatever) and a set of initial conditions, and then define the victory condition as achieving some other condition. It could be as simple as “To win, your enterprise must be worth $5 billion,” or it can be as complex as you like. You can also start the player in rapidly deteriorating conditions and challenge her to turn them around or simply to survive for a certain length of time.

Competition Modes

CSGs are almost always single-player games—though many online games such as FarmVille belong to a rather unusual competition mode, single-player cooperative. It’s possible to make them into multiplayer competitions, but competition discourages the kind of creative experimentation that CSGs are designed to support. If the players are sharing a game world and competing for the same resources, such as land or minerals hidden in the environment, the game becomes a race to see who can grab the most, ignoring the other aspects of play. If the players are operating in separate game worlds and have symmetric starting and victory conditions, the game tends to be about optimizing efficiency. If the conditions are asymmetric, the game will be difficult to balance.

CSGs let the player be playful, to build and experiment in the world you’ve given him. That’s seldom consistent with competition. One major exception is in hybrid games, those that have a military element as well as construction and management elements. The section “Hybrid Games,” later in this e-book, discusses these.

Simulating Individuals

Many CSGs simulate the behavior of a group of people (or ants, in the case of SimAnt) within an environment managed by the player. Games such as the original SimCity, which handle a large number of people, model behavior statistically rather than keeping separate values for each person. However, you might want to simulate the actions of particular individuals that the player can see moving around, as the modern versions of SimCity do. This will make your game a good deal more entertaining because the player can take an interest in the actions and progress of specific people. It appeals to a voyeuristic impulse and makes the consequences of the player’s decisions seem more personal. It’s particularly effective when the player can actually see unhappy people packing up and leaving.

Modeling individuals rather than statistical aggregates adds considerably to your design job. You will need to create a behavioral model and determine what aspects of the individual’s condition the player will be trying to optimize. For example, many such games include a single-valued variable that tracks a character’s degree of happiness or unhappiness and a set of needs that the simulated character desires to fulfill. Fulfillment may come as the result of the character’s autonomous action (driving from home to work fulfills the need to get to work) or from action taken by the player (building a school fulfills the characters’ need for educational opportunity). If a need goes unfulfilled, either through a problem that arises within the simulation (traffic jams prevent the person from getting to work) or because the player fails to act (no school has been built), there should be a negative consequence of some kind (the simulated person becomes unhappy).

Modeling individuals relieves you of the job of creating a statistical model because the behavior of the individuals collectively provides the statistics, but balancing such a game is a more intricate task. You will probably discover emergent behaviors—that is, unanticipated consequences of design decisions. Some of these will be fascinating and almost seem like intelligence, but others will clearly be degenerate: simulated people locked in a tight behavioral loop, for example, only ever doing one or two things because your needs mechanism isn’t balanced properly.

Behavioral modeling is too big a subject for us to address comprehensively here. Consult the references for further reading.

Mind Reading

If your game allows the player to select a simulated character—usually done by clicking the character with the mouse—you can offer another useful analytical tool: mind reading. To let the player know what’s on that individual’s mind, pop up an icon or even a whole dialog box showing the character’s internal state: current goal, degree of happiness, or whatever data might be useful to the player. This lets the player get a quick, rough sense of how the people feel without having to turn to a chart or a graph.

Advisors

Another tool commonly found in CSGs is the advisor: a game character who pops up from time to time and gives the player advice (see Figure 4). Because problems are often local to one area of the map, the player might be looking at another area when trouble occurs and not see it until it grows severe. By creating an advisor, you can warn the player of problem conditions wherever they occur. You might also consider including a screen button or menu item that moves the camera to the location of the most recently reported problem.

Figure 4 Theme Park World. Note the advisor in the lower-right corner.

In addition to warning of emergencies, an advisor can give the player information about the general state of the game: “The people need more food” or “Prices are too high.” This lets the player know of global problems without requiring her to consult the analytical tools.

To design an advisor, define both the local and the global problems that you think are important to let the player know about and then set the threshold levels at which the advisor will pop up. If the advisor will interrupt the player or say something aloud, don’t set these thresholds too low, or the constant interruptions will become irritating. You should also make it possible for the player to turn off the advisor or to consult it only when he wants to. Playing without the advisor adds an extra challenge to the game.

Pure Business Simulations

Pure business simulations allow players to construct only financial fortunes, not visible worlds. A game like Theme Park World is a business simulation because it’s about attracting customers and making profits, but because the player builds structures that exist in the virtual world, it is not a pure business simulation. Compare that with the game Hollywood Mogul, for example, which is a pure business simulation about the business of making movies. It consists only of a series of menu screens about hiring stars and making deals. The player never sees a set or a camera. Mr. Bigshot, shown in Figure 5, is a fairly simple stock-market simulation and is even more abstract than Hollywood Mogul.

Figure 5 Mr. Bigshot is a pure business simulation without a construction aspect.

Most of the challenges of designing a pure business simulation are the same as for any other management simulation: You must devise an economy and mechanisms for manipulating it. The real trick is to find some way of making the subject visually interesting. Spreadsheets and pie charts have limited appeal, so if you’re going to do a management simulation without a construction element, try to give it some kind of a setting or find a visual representation of the process that will make it attractive and compelling. Mr. Bigshot accomplishes this with lots of animation, voiceover narration, music, and cartoon characters representing the player’s opponents; the player feels rather like a contestant on a TV game show.

Capitalism II (see Figure 6), a huge, sprawling business simulation covering all kinds of products and industries, develops in a different direction. In addition to showing pictures of the products and all the raw materials that go into them, the game allows players to construct or purchase buildings in cities, so there’s an attractive SimCity-like view as well.

Figure 6 Capitalism II

Pure business simulations never have the pulse-pounding excitement of a first-person shooter, but fans find them highly enjoyable games. As the designer, you need to work closely with the art director to make the essentially numeric nature of the gameplay as lively as possible.

Hybrid Games

The Civilization, Dungeon Keeper, and Settlers series are all hybrid games, each one a cross between a CSG and a war game. In addition to their economic challenges, all feature exploration and conflict challenges. The military aspect of The Settlers is quite simple, as it must be, because the economic aspect is exceedingly complex. Minecraft is a hybrid of CSG and action-adventure. A few other games, such as Animal Crossing, feature construction as a smaller part of their gameplay. Dungeon Keeper begins each scenario with construction and management of a dungeon complete with semiautonomous denizens. In the later stages of the scenario, the player takes his army of creatures into battle, and the construction activities are finished. Control in Dungeon Keeper is a curious hybrid of direct and indirect control in that creatures have a distinct behavior model but obey orders as long as they’re happy. (Unhappy creatures disobey or even desert.) However, Dungeon Keeper retains its economic challenges throughout: It’s one of the very few games in which the troops have to be paid, fed, and given a place to sleep.

If you’re going to design a hybrid game in which construction and other activities depend heavily on the internal economy, design the essential elements of the economic simulation first (key resources, sources, and drains) and then add the other elements afterward. A mistake in the economic design can easily ruin the rest of the game.