FUNDAMENTALS OF GAME DESIGN, SECOND EDITION
The Temporal Dimension
The temporal dimension of a game world defines the way that time is treated in that world and the ways in which it differs from time in the real world.
In many turn-based and action games, the world doesn't include a concept of time passing: days and nights or seasons and years. Everything in the world idles or runs in a continuous loop until the player interacts with the game in some way. Occasionally, the player is put under pressure by being given a limited amount of real-world time to accomplish something, but this usually applies to only a single challenge and is not part of a larger notion of time in the game.
In some games, time is implemented as part of the game world but not part of the gameplay. The passage of time creates atmosphere and gives the game visual variety, but it doesn't change the game's challenges and actions. This usually feels rather artificial. If the player can do exactly the same things at night that she can during the day and no one ever seems to sleep, then there's little point in making the distinction. For time to really support the fantasy, it must affect the experience in ways besides the purely visual.
Baldur's Gate, a large role-playing game, is a good example of a game in which time is meaningful. At night, shops close and the characters in the game run an increased risk of being attacked by wandering monsters. It's also darker and hard to see. Taverns are open all day and all night, which is reasonable enough, but the customers don't ever seem to leave and the bartender never goes off shift. In this way, the game's use of time is a little inconsistent, but the discrepancy serves the gameplay well because you can always trade with the bartender and pick up gossip no matter what time it is. The characters do need rest if they've been on the march for a long while, and this makes them vulnerable while they're sleeping. In the underground portions of the game, day and night have less meaning, as you would expect.
In games that do implement time as a significant element of the gameplay, time in the game world usually runs much faster than in reality. Time in games also jumps (as it does in books and movies), skipping periods when nothing interesting is happening. Most war games, for example, don't bother to implement nighttime or require that soldiers get any rest. In reality, soldier fatigue is a critical consideration
in warfare, but because sleeping soldiers don't make exciting viewing and certainly aren't very interactive, most games just skip sleep periods. Allowing soldiers to fight continuously without a pause permits the player to play continuously without a pause also.
The Sims, a game about managing a household, handles this problem a different way. The simulated characters require rest and sleep for their health, so The Sims depicts day and night accurately. However, when all the characters go to sleep, the game speeds up considerably, letting hours go by in a few seconds. As soon as anyone wakes up, time slows down again.
The Sims is a rather unusual game in that it's chiefly about time management. The player is under constant pressure to have his characters accomplish all their chores and get time for sleep, relaxation, and personal development as well. The game runs something like 48 times as fast as real life, so it takes about 20 minutes of real time to play through the 16 hours of game-world daytime. However, the characters don't move 48 times as fast. Their actions look pretty normal, about as they would in real time. As a result, it takes them 15 minutes according to the game's clock just to go out and pick up the newspaper. This contributes to the sense of time pressure. Because the characters do everything slowly (in game terms), they often don't get a chance to water their flowers, which consequently die.
In The Settlers: Rise of an Empire, a complex economic simulation, a tree can grow from a sapling to full size in about the same length of time that it takes for an iron foundry to smelt four or five bars of iron. This is a good example of anomalous time: time that seems to move at different speeds in different parts of the game. Blue Byte, the developer of The Settlers, tuned the length of time it takes to do each of the many tasks in the game to make sure that the game as a whole would run smoothly. As a result, The Settlers is very well balanced at some cost to realism. However, it doesn't disrupt the fantasy because The Settlers doesn't actually give the player a clock in the game world. There's no way to compare game time to real time, so in effect, the game world has no obvious time scale (see Figure 4.7).
Another example of anomalous time appears in Age of Empires, in which tasks that should take less than a day in real time (gathering berries from a bush, for example) seem to take years in game time according to the game clock. Age of Empires does have a time scale, visible on the game clock, but not everything in the world makes sense on that time scale. The players simply have to accept these actions as symbolic rather than real. As designers, we have to make them work in the context of the game world without disrupting the fantasy. As long as the symbolic actions (gathering berries or growing trees) don't have to be coordinated with real-time actions (warfare) but remain essentially independent processes, it doesn't matter if they operate on an anomalous time scale.
LETTING THE PLAYER ADJUST TIME
In sports games and vehicle simulations, game time usually runs at the same speed as real time. An American football game is, by definition, an hour long, but because the clock stops all the time, the actual elapsed time of a football game is closer to three hours. All serious computerized football games simulate this accurately. Verisimilitude is a key requirement of most sports games; if a game does not accurately simulate the real sport, the league might not approve of it, and its competitors are bound to point out the flaw. However, most such games also allow the players to shorten the game by playing 5- or 10-minute quarters instead of 15-minute quarters because most people don't want to devote a full three hours to playing a simulated football game. This is also a useful feature in testing; it takes far too long to test the product if you have to play a full-length game every time.
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Flight simulators also usually run in real time, but there are often long periods of flying straight and level during which nothing of interest is going on; the plane is simply traveling from one place to another. To shorten these periods, many games offer a way to speed up time in the game world by two, four, or eight times—in effect, make everything in the game world go faster than real time. When the plane approaches its destination, the player can return the game to normal speed and play in real time.
