[In an in-depth Gamasutra analysis piece, Ellison looks at the universe and history of player-NPC dialogue interaction in games, analyzing titles from Mass Effect through Facade to The Sims and beyond.]
In 1966, Joseph Weizenbaum created ELIZA (pictured below), a computer program designed to emulate interaction between
the user and an artificial therapist. Ever since, designers of interactive
entertainment have attempted to incorporate meaningful interactions with
virtual characters in order to aid immersion.
The most popular Western RPGs, like the Baldur's Gate and Fallout series, live and die by the strength of their dialogue and
the player's ability to influence the non-player characters. Japanese romance
games such as Konami's Tokimeki Memorial
and visual novels like the Phoenix Wright
series revolve almost entirely around character interactions.
Even action titles like Grand
Theft Auto: San Andreas incorporate elements of non-violent character interaction to
make the world come to life. However, while a great deal has been written about
the process of creating game characters and writing for games, very little
literature has addressed the mechanics behind character interaction in games.
While likeable design and well-written dialogue are among
the most vital aspects in engaging a player with in-game characters, the
systems of interaction certainly play an important role as well.
NPC interaction gameplay is a part of nearly every modern
game, in the form of dialogue, barking orders at followers, or just choosing who
to talk to in town. However, the western games industry has always found it
difficult to create successful games based solely around character
interactions, even though such things are popular in other media (television,
The difficulties in interactive conversation lie in giving
the player the illusion of freedom while still feeling natural and driving the
story forward along interesting paths. Finding the most interesting and
engaging way for a player to interact with game characters and develop
relationships potentially opens up a wide array of game concepts and themes not
typically explored by western game developers.
NPC interaction gameplay has seen numerous permutations
throughout the years, but most can be separated into a few categories based on
common design patterns. Gameplay varies with regard to level of interactivity,
interface, and how the game presents the player with his potential responses. What
follows is an overview of the gameplay of character interaction to date.
In games using non-branching dialogue, the simplest form of
interaction, the player walks up to an NPC and initiates conversation. The NPC
delivers his or her lines and the conversation ends. Alternately, initiating a
conversation with an NPC triggers a cutscene where the player's avatar and the
NPC have a non-interactive dialogue.
If the player talks to the same NPC again
after certain events, the NPC may have different things to say, but the player
never has any control over the conversation. The only decision-making involved
is whether or not to talk to the NPC.
This type of interaction is extremely common and easy to
implement, and can therefore be seen in almost any game featuring non-hostile
NPCs, such as the original Final Fantasy
and The Legend of Zelda: Ocarina of Time.
While non-branching dialogue is still a regular facet of modern games, due to the
absence of gameplay it is included in this article only for reference.
Game dialogue becomes more interactive when conversations can
take different paths. The player reads dialogue and chooses their response from a
limited set of choices available to them. Conversation typically moves forward
such that the player cannot go back to previous topics or responses.
From this basic framework, NPC interaction can be as simple
as the player answering a yes or no question in a three-line conversation with
a random NPC in town, or as complex as the relationship-building simulations in
Japanese dating games like Tokimeki
In games where branching dialogue is the primary gameplay focus,
the player's choices often affect the NPCs' attitudes toward the player one way
or another, with the player attempting to guess the "best" response
in order to maximize NPC disposition.
One common technique employed to give the player a greater
illusion of freedom is to have multiple responses lead to the same path. This
is usually done as an attempt to limit the quantity of dialogue that must be
produced for the game. Therefore, branching dialogue usually curves back in on
itself such that while an individual choice may immediately produce a unique
response, the rest of the conversation is typically not unique to that choice.
In games where the goal of conversation is to improve the
player's relationship with the NPC, however, while every choice may not change
the course of the dialogue, each choice may have a different number of "mood
points" associated with it, and thus the player must still carefully
consider his options at every turn.