A mainstay of classic adventure games, as well as of many other genres, is dialogue between the player and other characters. NPCs, nonplayer characters, help to move the game forward, by dispensing clues, advice, snappy rejoinders, or witty observations. In the days of the text adventure, the player was able to construct sentences at will and try them out in various situations. In today’s graphic games, the most common type of conversation limits the player’s choices, by presenting only a handful of topics at a time. Both methods are based on the concept of a dialogue tree.
At its simplest, the player selects a topic ...