Persistent world

A persistent world (PW) is a virtual world that continues to exist even after a user exits the world and that user-made changes to its state are, to some extent, permanent. The term is frequently used in the definition of the massively multiplayer online video games and can be considered synonymous with that class of games, including other narrative forms of a media franchise.

Overview

The persistence comes from maintaining and developing a single or dynamic instance state of the world in the game around the clock shared and viewed by all players. Quite unlike other types of games, the plot and events in a single permainstance world game continue to develop even while some of the players are not playing their characters. That aspect is similar to the real world where events do occur regardless if they are directly or indirectly related to a person, as they continue to happen while a person is asleep, etc. Conversely, a player's character can also influence and change a persistent world. The degree to which a character affects a world varies from game to game. Since the game does not pause or create player-accessible back-up files, a character's actions will have consequences that the player must deal with.

Elements of persistent worlds can be found in computer games from as early as the 1980s, including Trade Wars (1984), Wasteland (1988), and Orb Wars (1989). Several video games from the 1980s also featured elements of persistent worlds with their own day-night cycles and non-player characters going about their own daily routines, including Konami's Castlevania II: Simon's Quest (1987), Nintendo's Zelda II: The Adventure of Link, T&E Soft's Hydlide 3: The Space Memories (1987), Fun Factory's War of the Dead (1987), and Chunsoft's Dragon Quest III (1988). Certain aspects of persistent worlds become more and more prominent in the Pokemon franchise beginning with Pokemon Gold.

The term "persistent world" gained popularity in the late 1990s with the growth in popularity of MMORPGs. The term is also frequently used by players of Neverwinter Nights (2002) and Neverwinter Nights 2 (2006) to refer to MMORPG-like online environments, such as Arkaz, Avlis, Dasaria, and The Known Lands (TKL) created using the game's toolkit.

Offline persistence

Persistent worlds can be simulated in offline games, such as in the Animal Crossing series. Even though nothing happens while the game is off (due to the obvious technical constraint), the illusion of persistence is created by advancing events as soon as the game is turned on. The game generates events that could have happened during the real-world time in which the game was inactive. NPC development is also seen as a key factor in maintaining offline and online persistence. A method for creating NPCs that evolve and adapt to gameplay is seen in research done on motivated reinforcement learning agents. Further persistence is possible if NPC interact with players in an adaptive way rather than a static method without regard to prior experiences. Another good example of offline persistence is in Metal Gear Solid 3. If one is to stop playing long enough during the boss fight with the End - he will die of old age in game. Perhaps the first game to use that technique is the game Noctis, where the players are advised to turn off the game when refueling (something that takes a long time), or when someone stops playing and returns while landed on a planet, and can see some visible changes, like sea level changes or daytime/nighttime cycles.

See also

• MUD
• Instance dungeon