Dialogue tree

Example of a simple dialog tree.

A dialog tree or conversation tree is a gameplay mechanic that is used throughout many adventure games (including action-adventure games) and role-playing video games. When interacting with a non-player character, the player is given a choice of what to say and makes subsequent choices until the conversation ends.

History

The concept of a dialog tree has existed long before the advent of video games. The first dialog tree is evident in a story known as The Garden of Forking Paths where all major outcomes from an event branch into their own chapters. Much like the game counterparts this story reconvenes as it progresses (as possible outcomes would approach n^m where n is the number of options at each fork and m is the depth of the tree).

Game mechanics

The player typically enters the gameplay mode by choosing to speak with a non-player character (or when a non-player character chooses to speak to them), and then choosing a line of pre-written dialog from a menu. Upon choosing what to say, the non-player character responds to the player, and the player is given another choice of what to say. This cycle continues until the conversation ends. The conversation may end when the player selects a farewell message, the non-player character has nothing more to add and ends the conversation, or when the player makes a bad choice (perhaps angering the non-player to leave the conversation). Games often offer options to ask non-players to reiterate information about a topic, allowing players to replay parts of the conversation that they did not pay close enough attention to the first time.

These conversations are often designed as a tree structure, with players deciding between each branch of dialog to pursue. Unlike a branching story, players may return to earlier parts of a conversation tree and repeat them. Each branch point (or node) is essentially a different menu of choices, and each choice that the player makes triggers a response from the non-player character followed by a new menu of choices. In some genres such as role-playing games, external factors such as charisma may influence the response of the non-player character or unlock options that would not be available to other characters. These conversations can have far-reaching consequences, such as deciding to disclose a valuable secret that has been entrusted to the player.

Value and impact

This mechanism allows game designers to provide interactive conversations with nonplayer characters without having to tackle the challenges of natural language processing in the field of artificial intelligence. In games such as Monkey Island, these conversations can help demonstrate the personality of certain characters.

See also

• Digital conversation
• Adventure game
• Action-adventure game
• Sierra Entertainment