Difference between revisions of "Irreversible Events"

Revision as of 20:15, 30 March 2011

Events whose effect on the game state cannot be undone.

All events in a game affect the game state but many may be countered by another events, e.g. a movement in one direction may be countered by a movement in the opposite direction. Game state changes that cannot be revert back in this way are the effects of Irreversible Events. These type of events guarantee that the gameplay progresses according to a certain design and may be used to clearly indicate changes in what is the current focus of the gameplay to players and, if the player can choose to do the actions that cause the events, can give players more meaningful choices.

Examples

Pushing a box into a corner in Sokoban is an Irreversible Event since the box cannot be moved from there, as the boxes can only be pushed and not pulled.

The Ko (and meta Ko) rule in Go is used to make it impossible for the game to run into infinite loops and without these some events in the game would be reversible.

Using the pattern

To really enforce that events are irreversible in games they need to have Dedicated Game Facilitators, including Game Masters (but the latter may also make this assumption invalid). Other games may have them in the rules but these may not be followed.

Even though Real-Time Games make it impossible to undo actions (without resorting to Save-Load Cycles or Game Time Manipulation) this does not automatically create Irreversible Events since later action may cancel the effect of earlier ones. Making events into Irreversible Events can be done by making sure that all other events in the whole game design do not affect a specific part of the game state (other events may affect that part of the game state as long as all affect it in the same way or direction). Other ways of making Irreversible Events are to make actions use Non-Renewable Resources (in which case the action rather that the consequences of the action may be Irreversible Events) or create events that give players information. Designed Surprises are thus a form of Irreversible Events, and since they are a form of Trans-Game Information, they are even Irreversible Events across game sessions. Events that provide Strategic Knowledge are likewise Irreversible Events since these also generate Trans-Game Information.

The possibility of Saving makes it impossible to have totally Irreversible Events in a game if players are willing to make use of Save-Load Cycles. This can be countered to a certain extent by causing actions to have Delayed Effects (c.f. The Witcher) at the cost of Predictable Consequences.

Irreversible Events can be instantiated in many different forms. Switches and Alarms are game elements that can be used to enforce Irreversible Events, in the first case by not being able to be activated more than once and in the second case by not being able to be deactivated once activated (or vice versa). A typical example of a class of Irreversible Events is Leaps of Faith, which forces players to dedicate themselves to a certain movement in the game. Quick Travel is another type of movement that easily can be an Irreversible Event if one cannot come back to the old space - the most common example of this is probably being moved to one Level after completing another with no possibility of returning. Making the Transfer of Control of Resources into Irreversible Events is part of creating Non-Renewable Resources, while using Irreversible Events in conjunction with Loyalty or the creation of Enemies is a way of creating parts of Narration Structures. Revealing oneself as a Traitor or committing a noticeable Betrayal are both examples of Irreversible Events since they make players change their allegiances (and even if they later change back this will very likely permanently lowered their reliability). These latter types of events, which reveal aspects of what kind of Character a player is portraying, can be explicitly designed as Character Defining Actions and by performing them they become Irreversible Events. In this way, Irreversible Events can modulate how a Character's Open Destiny evolves during gameplay.

Irreversible Events can be created to be the consequences of actions but the actions themselves do not have to be irreversible - their effect may be since partly or completely prevented if they are Interruptible Actions. Likewise, actions that cause Ultra-Powerful Events do not have to be Irreversible Events since other Ultra-Powerful Events may counter the event after it is completed. An example of this is Shrinking Game Worlds: these are usually Ultra-Powerful Events that cannot be affected while they are occurring but after the Game World has become smaller it may at a later stage expand again.

One of the possibilities of Irreversible Events is that they can function as Closure Points since after they have occurred one can know that some parts of the game state are irrelevant for future gameplay.

Consequences

Every Irreversible Event that a player understand to be irreversible is a closure. Although this can indicate progress or failure clearly, the presence of the pattern may negatively affect Experimenting since there is no Reversability, and make Puzzle Solving more difficult. Rather, the presence of Irreversible Events promote Stimulated Planning and may cause Analysis Paralysis.

Irreversible Events are required to progress Narration Structures and can be used to provide a condensed history of gameplay in a game session without losing any events that affected the final outcome. Leaving a Level and not being able to come back to it is an example of how a Narration Structure can be maintained by Irreversible Events. An example of how Irreversible Events can advance the Narration Structure in Real-Time Games without relying on Levels is to move the places where Spawning occurs.

The synthesis of having a Freedom of Choice between several Irreversible Events is one way to create Internal Conflicts.

For cases where a Construction is an Irreversible Event, this can provide an increased Value of Effort to the Construction since players do not need to worry about them being destroyed.

Quite naturally, Irreversible Events are incompatible with Free Game Element Manipulation although this may break game rules. Given that Game Masters decide what the rules are, these may whenever they wish reverse events while simultaneously change the rules (they may of course enforce the effect of events as they wish also).

Relations

Can Instantiate

Analysis Paralysis, Closure Points, Enemies, Internal Conflicts, Narration Structures, Stimulated Planning

with Construction

Value of Effort

Can Modulate

Alarms, Construction, Game Worlds, Levels, Loyalty, Open Destiny, Puzzle Solving, Shrinking Game World, Spawning, Switches, Transfer of Control, Ultra-Powerful Events

Can Be Instantiated By

Betrayal, Character Defining Actions, Dedicated Game Facilitators, Game Masters, Leaps of Faith, Non-Renewable Resources, Quick Travel, Surprises, Traitors, Trans-Game Information

Can Be Modulated By

Interruptible Actions

Possible Closure Effects

-

Potentially Conflicting With

Experimenting, Free Game Element Manipulation, Game Masters, Predictable Consequences, Save-Load Cycles

History

An rewrite of the original pattern named Irreversible Actions in the book 'Patterns in Game Design' (Björk & Holopainen, 2004).

References

Björk, S. & Holopainen, J. (2004) Patterns in Game Design. Charles River Media. ISBN1-58450-354-8.