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. Certain video game genres, such as visual novels and dating sims, revolve almost entirely around these character interactions and branching dialogues.

The concept of a dialog tree has existed long before the advent of video games. The earliest known dialog tree is described in "The Garden of Forking Paths," a 1941 short story by Jorge Luis Borges, in which the combination book of Ts'ui Pên allows 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).

The first computer dialogue system was featured in ELIZA, a primitive natural language processing computer program written by Joseph Weizenbaum between 1964 and 1966. The program emulated interaction between the user and an artificial therapist. With the advent of video games, interactive entertainment have attempted to incorporate meaningful interactions with virtual characters. Branching dialogues have since become a common feature in visual novels, dating sims, adventure games, and role-playing video games.

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