Portal (1986)

Portal is a mix between a computerized novel and an interactive game. It was published for the Amiga in 1986 by Activision, written by Rob Swigart, produced by Brad Fregger, and programmed by Nexa Corporation. Versions for the Commodore 64, Apple II, and MS-DOS were later released. Versions for the Apple Macintosh and Atari ST were announced and developed, but never formally released. A unique game for its time, Portal was one part text-driven adventure (à la Zork or Planetfall) but with a graphical interface. It is unrelated to the 2007 game of the same name by Valve Corporation.