Game Features

Strategy games can either be turn-based or played in real time. Pure strategy games (those that contain only conflict challenges, with no economic or physical challenges) tend to be turn-based rather than operating in real time. In a turn-based game, players may mull over their moves, considering the benefits of one choice over another. In board games, this can result in frustrating “analysis paralysis” in which one player spends a large amount of time considering each move while the others have to wait. In single-player computer games, this doesn’t matter—the computer doesn’t mind waiting. Multiplayer turn-based computer games are often designed so that all the players choose their next move simultaneously, and the machine computes and displays the outcome of their actions; mobile and Facebook games often allow players to play asynchronously during free moments. This cuts down substantially on the waiting time.

Real-time strategy (RTS) games developed after turn-based games. RTSs added time pressure to strategy games because everything happens at once and players do not have individual turns to ponder their moves. Although they’re not as frenetic as action games, RTSs require the player to keep a sharp lookout and to think quickly.

Many books have been written about games such as chess and Risk, so we won’t spend much time on abstract strategy games or those with simple rules. The vast majority of computerized strategy games are representational war games with complex core mechanics, so that is where we’ll focus our attention.

Challenges

As the definition says, strategy games may include economic and exploration challenges, but strategic conflict generally dominates in strategy games. A game that includes only economic challenges without any fighting is more properly a construction and management simulation (CMS). For example, exploration and growth do feature in StarCraft, but only to enable the player to fight more effectively; players must explore the area to be conquered and set up resource-processing factories for converting resources into troops and vehicles.

Strategic Conflict

Conflict is most often characterized as combat between groups of individual combatants; by long tradition, these combatants are known as units. A unit can be anything from an ancient Egyptian warrior to a Napoleonic cavalryman to an imaginary spacecraft. Not all units fight; some can be used for transport, scouting, or other purposes. Units also need not be movable; a fixed gun emplacement is still a unit. In most modern war games, specialized units, often portrayed as buildings, are used to produce new fighting units. Generally these buildings don’t move and don’t fight, but they can be destroyed if attacked and perhaps can be repaired by repair units. Although it is not an industry standard term, this e-book refers to such buildings as factories. In general, the term units will mean fighting units, not factories.

The main characteristic that distinguishes units and factories from anything else on the battlefield is that they are under a player’s control and provide some benefit to him, so if they die or are destroyed, that benefit is lost to the player. Units may be atomic, with no individually distinguishable parts (such as an infantry soldier with a rifle), or compound, with separate parts that can be added, removed, and perhaps destroyed without completely destroying the whole unit (such as a large ship with many guns). Each unit behaves according to particular performance characteristics, such as how long it can survive when under attack, how rapidly it can fire a weapon, or how fast it can move. The later section “Core Mechanics” discusses these attributes in more detail.

To give the player interesting options, almost all war games offer the player a choice of different kinds of units. In chess, there are six kinds; in more representational games, there may be dozens. Checkers starts with only one kind of unit, but later in the game a new kind can appear: a king.

Most war games seek to reproduce the classic situations and tactics of military combat, whether at particular points in history or in imaginary conflicts. Depending on the degree of realism offered, tactics can include flanking maneuvers, sneak attacks, creating diversions, cutting off enemy supply lines, killing superior officers to leave troops without leadership, taking advantage of the effects of bad weather, and so on. In order for the player to use these tactics, the units and the rules of the game have to be designed in such a way as to support them. If you want your game to include sneak attacks, for instance, you’ll have to include a mechanism that hides the enemy’s movements from the player. Obviously on some level the computer knows everything that is happening, but you can design the computer’s artificial intelligence (AI) to ignore the player’s movements if the software determines that the player’s units are not visible to the computer’s troops.

Alternatives to Combat

Conflict does not necessarily involve physical combat. Whereas RTS games and simpler strategy games tend to focus on combat, more advanced games include elements of diplomacy, crisis management, and espionage. For example, in Civilization III, the response of the enemy leaders to diplomatic overtures depends in large part on whether the player has the force to back up her tough words. Of course, diplomacy isn’t all about threatening enemies—it also allows the player to form alliances that can avert war and encourage trade.

Diplomacy and espionage suit a slower-paced strategy game, one designed to be played over a long period of time. The extra nuance and depth that diplomacy adds to an otherwise standard strategy game is well worth the extra time and effort spent designing and implementing a full-fledged system of diplomats and spies. Diplomacy gives the player an extra degree of freedom that allows her to create more devious and interesting game plans than would be possible otherwise.

Nevertheless, strategy games tend to reward aggressive measures more than they do peaceful ones because war is easier to model, and more exciting to watch, than diplomacy. The consequences of war are presented as less dire than they are in the real world, and the goal of the game is often domination of the world, not peaceful coexistence. It would be interesting to see a strategy game whose goal was to avert war and promote prosperity; the player’s role would perhaps be the secretary-general of the United Nations.

Exploration Challenges

Exploration lets players investigate unknown terrain in a game world. As a designer, you may give the player new worlds or make creative use of the familiar world. Consider X-COM: UFO Defense, which depicts the secretive invasion of Earth by aliens. Of course players are familiar with the map of Earth, but the location of hidden alien bases and UFO landing sites is a mystery until the player sends out a squad of soldiers to investigate.

X-COM presents the player with a landscape shrouded in darkness, a darkness that dissipates only when the player’s soldiers enter an area. This technique is used in most strategy games involving exploration to increase their difficulty. If the terrain is generally flat, you can decide that the area to be revealed is simply a circle of a certain diameter around a unit, but in hilly terrain you may wish to compute the actual lines of sight for the units so that enemy units behind hills or other obstructions remain hidden. The level design in many single-player war games uses the player’s ignorance of the landscape heavily; to win a level, for instance, the player may have to explore enough to find some key feature, such as a bridge over an impassable river or a back way to sneak up on the computer player’s headquarters.

Games often present territory that has been explored—but currently is not patrolled by the player’s forces—as dim, with only landscape details and no information about the presence of enemy units. These two techniques—unexplored regions shown in black and explored but unpatrolled regions shown dimly—are known collectively in games as the fog of war. Figure 1 shows the bright area currently visible to the player, the dimmed area that has been explored but is not currently visible (due to lack of troops there to provide intelligence), and the black bulk of the land that remains unexplored.

Figure 1 The fog of war from Civilization III

The fog of war lends realism and excitement to the game. Because the player cannot see what is happening in areas where he has no troops, he could be attacked unexpectedly if he does not take appropriate defensive measures. These games reward those who set up guard units to warn of impending invasions and those who send out scouts to find out where the enemy is.

Hiding the unexplored landscape itself, however, is completely unrealistic in any game set after about the year 1500. Armies haven’t had to fight wars without a map of the terrain for several centuries. Games continue to hide the landscape from the player because the task of exploring makes the game more challenging. In a lot of games, if the player can see the landscape clearly, she is able to plan more effectively and therefore win more quickly. Many games also cheat, hiding the landscape from the player but allowing the computer’s AI to see it. This gives the computer an advantage that the player does not have and helps to compensate if the AI isn’t very good in the first place. It’s a design solution to a programming problem: weak AI.

Economic Challenges

The sinews of war: a limitless supply of money.

—Cicero

Strategy games such as chess give the players a fixed number of units at the beginning of the game, and the players make do with what they’ve been given. Other games offer a mechanism for acquiring more units as the game goes on, which makes the campaign more a process of growth than of attrition. In tower defense games, for example, the player gets money, which he can invest in new towers between waves of enemies.

Computer strategy games allow for far more complex calculations than a human being playing Risk is willing or able to perform. Frequently designers of computer strategy games take advantage of this to include a richer internal economy for the player to manage. Rather than starting with a large number of units at the beginning of a level, the player has to obtain some resource—let’s assume it’s gold—that she can convert to units later on. This lets her decide when to buy the units and what sorts of units to purchase, and therefore offers her greater freedom to fight the battle in whatever way she prefers.

You can supply players with a limited amount of gold at the beginning of a level and put more gold out in the landscape for them to discover. These locations, or mines, can produce either a limited or an unlimited amount of gold. If mines produce an unlimited amount, the game could, in principle, go on forever; if not, the game must eventually come to an end as the resource runs out.

More complicated games use several different resources; in fact, if the economy of a strategy game becomes complicated enough, the game really turns into a hybrid of strategy game and CMS. The Age of Empires and Civilization series are both really hybrids, not straight strategy games, but we’ll look at the economy within Age of Empires as an example here.

In Age of Empires, the player must obtain food, wood, stone, and gold, each from its source, worked by units designated for the purpose and brought back to a central storage area. The player spends resources to construct factories, and in turn the factories produce units (which also consumes resources). The factories effectively form the player’s headquarters and must be defended, adding a new conflict challenge.

Player Actions

In a strategy game, the player’s role is that of a commander or manager, so most actions consist of giving orders to units. Each unit responds to commands according to the AI programming for that unit or type of unit. Giving an order is usually a two-step process: First, the player selects the unit or units that will receive the order, usually by clicking it. Then the player issues the order, either by clicking somewhere in the landscape, on an enemy unit, or on a button or menu item. Here’s a short list of actions and orders commonly occurring in strategy games (different games will use different names for them):

• Move to a given location in the terrain, optionally via a series of waypoints marked along the way. The unit uses pathfinding AI to find its way there, taking the quickest route while avoiding obstructions.

• Attack an enemy unit, which includes advancing until the enemy unit is in range, then opening fire, and pursuing if the enemy retreats.

• Stop moving; this order countermands both attack and movement orders. Because the AI for attacking usually pursues an enemy unit to the ends of the earth (including right into an ambush), the player frequently needs to issue the stop order.

• Hold a particular position, meaning attack any enemy that comes into range but do not pursue it if it retreats. The unit’s AI may include an automatic tendency to attack certain enemies preferentially, or the player may have to manage this directly.

• Establish a formation that is tactically advantageous. Loose infantry formations give some protection against archery because a lot of arrows fall into empty space; tight formations are best against other infantry. Warships with guns along their sides can concentrate their firepower if several sail in a straight line, head to stern. Tanks with guns at the front can do the same if their formation is abreast. You may want to include a formation editor in your game that lets the player design formations that he likes.

• Produce new units by consuming resources. This can be a command that the player gives by choosing a menu item or clicking a button on an overlay, but more often, the player gives the command to a specific factory whose function is to create mobile units.

You might want to consider variants of these common orders, such as

• Retreat, a movement toward safety that leaves the unit more vulnerable while moving but advances more quickly than ordinary movement.

• Dash, a rapid forward movement in which the unit does not attempt to attack enemies it encounters but tries to get to its destination as quickly as possible.

• Patrol, a cyclic movement between two or more designated points, allowing units to defend more territory than the hold command permits.

Figure 2 is from StarCraft showing, at the lower right of the screen, a menu of buttons that correspond to five of these commands. They are, from top to bottom and left to right, dash, stop, attack, patrol, and hold. The remaining visible icon invokes a special capability of the currently selected unit.

Figure 2 The StarCraft screen, with a menu of orders at the lower right

Specialized units have their own special orders, of course: building for construction units, healing or repairing medical or repair units, picking up and dropping off troops or supplies for transport units, and so on. The next section discusses specialized units.