Techniques & Technology

AGI Engine

Sierra's Adventure Game Interpreter

Sierra's AGI engine powered early graphical adventures from King's Quest to Space Quest, defining the parser-based adventure game genre.

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Overview

The Adventure Game Interpreter (AGI) was Sierra On-Line’s game engine from 1984-1988. It combined 160x200 graphics with a text parser, creating games where players typed commands while viewing illustrated scenes. AGI powered King’s Quest, Space Quest, Leisure Suit Larry, and other series that defined the genre before point-and-click interfaces.

Fast facts

  • Developer: Sierra On-Line.
  • Era: 1984-1988 (superseded by SCI).
  • Resolution: 160x200 in 16 colours.
  • Interface: text parser input.
  • Scripting: custom interpreted language.
  • Notable games: King’s Quest I-III, Space Quest I-II, Police Quest, Leisure Suit Larry.

Technical approach

How AGI worked:

  • Priority screens: layered graphics for depth.
  • View resources: animated character sprites.
  • Logic scripts: game behaviour programming.
  • Parser: natural language command interpretation.

Evolution to SCI

AGI gave way to improvement:

  • SCI engine (1988): higher resolution, mouse support.
  • Point-and-click: replaced text parser.
  • Sound: improved audio capabilities.
  • Legacy: AGI games still playable through ScummVM.

See also