Episodes and Sequences (1989)


In a blog post now only available from the Internet Archive, Doug Sharp (1989) describes the "battle" of interactive fiction from a GDC 1989 talk on the same topic. Within the post, Sharp (1989) mentions a project called King of Chicago (1989) and how it is an "honorable failure." Toward the end of the post, Sharp (1989) writes about a design of a "big bags with smaller bags inside which hold clips, which I called episodes." Each one of these episodes would:

specif[y] things like who is to be onscreen, chooses background graphics, switches between close-ups and medium shots, drives the character’s animation and facial expression, and feeds dialog to them. The episode script reads a lot like a playscript or screenplay. A single episode might put Pinky and his girlfriend Lola in her bedroom, and have her badger Pinky about earning more money. This episode might take two minutes of screen time.

- Sharp (1989)

In the following paragraphs, Sharp (1989) relates the interface between the state (collection of values) and how it affects episode navigation. As Sharp (1989) writes it: "The episode selector looks at all the keys of available episodes and selects the one that most closely matches current game variables. Its method is to look for a least square fit."

In pulling from the model Sharp (1989) writes about, there are several major concepts:

  • Story: Multiple episodes, each govern by character
  • Episode: Selection of sequences influenced by player actions within rules of player interactions
  • Narrator: decides episode order and when each ends
  • Sequences: set of phases (act-like structure within an episode)
  • Actions: player input

A story starts with an episode, composed of sequences. The player takes actions, which changes the values watched by the Narrator. This affects which sequences are chosen next, if the episode ends, and any future changes carried over into future episodes. When the episodes are exhausted, play ends.


Sharp, D. (1989). Story vs. Game: The Battle of Interactive Fiction. Computer Game Developer's Convention 1989. Retrieved from https://web.archive.org/web/20040404061317/http://www.channelzilch.com/doug/battle.htm

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