Timekeeping in games

In video and other games, the passage of time must be handled in a way that players find accurate and easy to understand. This is usually done in one of two ways:

Real-time

In real-time games, game time progresses continuously according to the game clock. Players perform actions simultaneously as opposed to in sequential units or turns. Players must perform actions with the consideration that their opponents are actively working against them in real time, and may act at any moment. This introduces time management considerations and additional challenges (such as physical coordination in the case of video games).

Real-time gameplay is the dominant form of time-keeping found in simulation video games, and has to a large degree supplanted turn-based systems in other video game genres as well, for instance real-time strategy. Time is an important factor in most sports; and many, such as soccer or basketball, are almost entirely simultaneous in nature, retaining only a very limited notion of turns in specific instances (i.e. a free kick in soccer or a free throw in basketball). In the card games Nertz and Ligretto, players must compete to discard their cards as quickly as possible and do not take turns.

While game time in video games is in fact subdivided into discrete units due to the nature of computing, these intervals or units are typically so small as to be imperceptible to the player.

Turn-based

In turn-based games, game flow is partitioned into well-defined and visible parts, called turns. A player of a turn-based game is allowed a period of analysis (sometimes bounded, sometimes unbounded) before committing to a game action, ensuring a separation between the game flow and the thinking process, which in turn presumably leads to more optimal choices. Once every player has taken his or her turn, that round of play is over, and any special shared processing is done. This is followed by the next round of play. In games where the game flow unit is time, turns may represent such things as years, months, weeks or days.

Turn-based games come in two main forms depending on whether, within a turn, players play simultaneously or take their turns in sequence. The former games fall under the category of simultaneously-executed games (also called phase-based or "We-Go"), with Diplomacy being a notable example of this style of game. The latter games fall into player-alternated games (also called "I-Go-You-Go", or "IGOUGO" for short), and are further subdivided into (A) ranked, (B) round-robin start and (C) random—the difference being the order under which players start within a turn: (A) the first player being the same every time, (B) the first player selection policy is round-robin, and (C) the first player is randomly selected. Some games also base the order of play on an "initiative" score that may in part be based on other, outside factors as well as dice rolls.

The term turn-based gaming can also be used to refer to browser-based gaming sites that allow for game-play to extend beyond a single session, over long periods of time—often taking months for complex games like Go or chess to finish.

Sub-types

Various adaptations of the real-time and turn-based systems have been implemented to address common or perceived shortcomings of these systems (though they often introduce new issues that did not exist before). These include:

Timed turns

Timed turns are designed to resolve issues of fairness where one player uses a greater amount of time to complete his or her turn than another player. In chess, for instance, a pair of stop clocks may be used to limit the time taken by the player to make his or her move in order to place an upper limit on the game length.

In exchange chess, four players on two teams play on two boards with each team taking one white and one black side. Any taken piece is given to a teammate, and can be placed on his board as a standard move (in any position that does not put his opponent in check). A common strategy is to gain a temporary material advantage, pass it on to a teammate, and then stop playing on one's own board—thereby allowing the teammate to use the advantage for many future moves on his board. To avoid this, players are often limited to ten seconds per move—with their opponent being allowed to remove one of the player's pawns from the board for each ten seconds taken.

The early Ultima games were strictly turn-based, but if the player waited too long to issue a command, the game would issue a "pass" command automatically, thereby allowing enemies to take their turns while the player characters did nothing. Further, many browser-based games allocate a number of turns that can be played within a certain period of time, called a tick (see next section).

Ticks

A tick-based game is a game that is played using ticks, or units of time. Not to be confused with a game round, a tick can be any measurement of real time, from seconds to days or even months, and is the basic unit upon which all important game actions take place. Players in tick-based games are allocated a certain number of turns per tick, which are subsequently refreshed at the beginning of each new tick. Predominantly found in browser-based MMORPGs, tick-based games differ from other turn-based games in that ticks always occur after the same amount of time has expired. Conversely, in a typical turn-based game, a turn would end only once every player has made all of his or her moves. In real-time games players are not limited, time-wise, in the number of actions they can take.

Rounds

In some real-time games, a notion of rounds exists, whereby game actions are timed according to a common interval that is longer than 'real time'. For instance, units might only begin or cease to act at the beginning or end of a round. In games such as the Baldur's Gate series, the notion of rounds is carried over in part from the pen-and-paper rule systems they are based upon. A similar (but unrelated) example is when a game unit's ability to act is limited by the length of its combat animation. The unit may become unresponsive until the animation has completed.

Online turn-based gaming uses the term "rounds" differently: in these games a round refers to when a new game begins following the completion of a previous one.

Active Time Battle

Hiroyuki Itō introduced the "Active Time Battle" system in Final Fantasy IV (1991), where the time-keeping system does not stop. Square Co., Ltd. filed a United States patent application for the ATB system on March 16, 1992, under the title "Video game apparatus, method and device for controlling same" and was awarded the patent on February 21, 1995. On the battle screen, each character has an ATB meter that gradually fills, and the player is allowed to issue a command to that character once the meter is full. The fact that enemies can attack or be attacked at any time is credited with injecting urgency and excitement into the combat system. The ATB system was fully developed in Final Fantasy V (1992) and continued to be used in most later Final Fantasy console role-playing games until Final Fantasy X-2 (2003) as well as other Square games such as Chrono Trigger (1995).

Time compression

Time compression is a feature commonly found in real-time games such as flight simulators, that allows the player to speed up the game time by some (usually adjustable) factor. This permits the player to shorten the duration of relatively uneventful periods of gameplay.

Simultaneously-executed turns

In simultaneously-executed games (also called "phase-based" or "We-Go"), turns are separated into two distinct phases: decision and execution. During the decision phase each player plans and determines his units' actions. The decision phase occurs at the same time for everyone, so there is little wait for anyone to finish. In the execution phase, all players' decisions are put into action, and these actions are performed more or less automatically and at the same time. The execution phase is non-interactive, and there is no waiting for other players to complete their turns. Examples include Laser Squad Nemesis, and the Combat Mission and Master of Orion series.

Clock-based

Clock-based games tie all unit actions directly to the game clock. Turns begin and end depending on the duration specified for each action, resulting in a sequence of turns that is highly variable and has no set order. This system is frequently cited for its realism when compared to other turn-based systems. It is also possible in this system for different players' actions to occur at the same time with respect to the game clock, as in real-time or simultaneously-executed games. Examples of games that use this type of system include Typhoon of Steel and MechForce, both originally for the Amiga.

Unit initiative

In some games the sequence of turns depends on the initiative statistic of each unit no matter which side the unit belongs to. Games of this type are still technically sequential (e.g. "I-Go-You-Go"), as only one unit can perform an action at a time, and the duration of actions is not tied to the game clock. Examples include The Temple of Elemental Evil and Final Fantasy Tactics Advance.

Acting outside one's turn

Some games—notably, the X-COM series of video games and the board wargame, Advanced Squad Leader—allow players to act outside of their normal turn by providing a means of interrupting an opponent's turn and executing additional actions. Typically, the number and type of actions a player may take during an interrupt sequence is limited by the amount of points remaining in the player's action point pool (or something similar) carried over from the previous turn.

The Silent Storm video game series includes an "Interrupt" statistic for each character to determine the likelihood of out-of-turn action. In M.A.X., defensive units may be set to fire out of turn at the expense of being able to fire in their own turn. In Tide of Iron, you may play a card that allows you to interrupt an opponent's turn and perform an action. In both Mario & Luigi: Superstar Saga and Mario & Luigi: Partners in Time, the player has a chance to "counterattack" on the enemy's turn, causing damage.

Special turns or phases

In some turn-based games, not all turns are alike. Imperium Romanum II, for instance, features a "Taxation and Mobilization" phase in every third turn (month), which does not occur in the other turns. In Napoleon, every third player turn is "night turn" where combat is not allowed.

Other turn-based games feature several phases dedicated to different types of activities within each turn. In the Battle Isle series players issue movement orders for all units in one phase, and attack orders in a later phase. In Agricola turns are divided into three phases: "Upkeep", "Replenishing" and "Work". A fourth phase, "Harvest", occurs every few turns.

Partially or optionally turn-based and real-time

Many other games that are not generally turn-based retain the notion of turn-based play during specific sequences. Notably, the role-playing computer games Fallout and Silent Storm are turn-based during the combat phase, and real-time throughout the remainder of the game. This speeds up portions of the game (such as exploration) where the careful timing of actions is not crucial to player success. Some turn-based games have been criticized for omitting this feature.

Other games (e.g. the Total War series) combine a turn-based strategic layer with real-time tactical combat, or (e.g. X-COM and Jagged Alliance 2) a real-time strategic layer with a turn-based tactical layer.

The video games X-COM: Apocalypse, Fallout Tactics and Arcanum offered players the option to play in either turn-based or real-time mode via an configuration setting. In the latter game's case both modes were criticized for being poorly balanced and overly simplified.

Real-time with pause

In real-time games with an active pause system (also called "real-time with pause", "pausable real-time" or "smart pause"), players are able to pause the game and issue orders. Once a game is unpaused, orders are automatically put into effect. This resolves issues players encounter where orders must be given to multiple units at the same time (normally an impossibility in real-time games), or where players need extra time for analysis before issuing actions. Players can often also configure the game to automatically pause when certain conditions are met, such as at the end of a round or upon the death of a non-player character. This option is not viable for multiplayer games, however, due to the interruption to the game flow.

The real-time with pause system was popularized by the Baldur's Gate series of role-playing video games, though it is also present in the pioneering RTS, Homeworld, as well as the RPG Darklands. "Smart Pause Mode" is also an advertised feature of Apeiron's Brigade E5: New Jagged Union and 7.62 mm.

Real-time vs. turn-based gameplay

A debate has emerged between fans of real-time and turn-based video games (usually some type of strategy or role-playing game) based on the merits of the real-time and turn-based systems.

Various arguments are made by proponents. Arguments made in favor of turn-based systems include:

• Players are able to plan their moves to a greater degree given the extra time available to them, and game designers are able to cater to these players by offering more tactical options.
• Games are more fair due to a lack of reliance upon player reflexes, and games can in theory have better artificial intelligence due to the greater amount of computer processing power available to them.
• It is more realistic to control multiple units intelligently using this system, as the player does not have to divide his or her attention among multiple groups of units.
• It is easier to keep track of what the enemy is doing since the player is informed of every enemy move (not taking into account fog of war).

Arguments made in favor of real-time systems include:

• Armies taking turns and acting sequentially is unrealistic. Real combat occurs simultaneously.
• Sitting around and waiting for turns to end can be tiresome.
• Thinking (and acting) quickly is part of the strategy and constitutes an additional element of challenge.
• Real-time systems are exciting and add to players' sense of immersion.
• Turn-based systems originally existed out of necessity due to hardware restrictions, not due to any added elements of realism.
• Turn-based games have too many rules and are difficult to master due to the number of minutiae they simulate.

See also

• Real-time strategy
• Turn-based strategy
• Real-time tactics
• Turn-based tactics
• Role-playing game (video games)

External links

• Time Systems - RogueBasin - Discusses several different types of timing systems used in roguelikes.