Time-keeping systems in games

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

In real-time games, game time progresses continuously according to the game clock. One example of such a game is the sandbox game Minecraft, where one day-night cycle is equal to 20 minutes in real time. 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, such as the free kick in soccer and the free throw and shot clock 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 sequential nature of computing, these intervals or units are typically so small as to be imperceptible.

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 better 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 periods such as years, months, weeks or days.

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