The Eidolon was one of two games in Lucasfilm Games' second wave. The other was Koronis Rift. Both took advantage of the fractal technology developed for Rescue on Fractalus!, further enhancing it. In The Eidolon, Rescue's fractal mountains were turned upside down and became the inside of a cave. Charlie Kellner was the project leader, designer, and lead programmer for this game.
The game was supplied on a flippy disk. One side had the Atari version, the other side had the Commodore 64 version. Due to the memory requirements (64kB), the Atari version would only run on an XL/XE with 64kB or more memory.
The Eidolon is an early example of the steampunk style in video games.
This advertisement, shown in a computer magazine, shows a contest that allowed you spend the day at Lucasfilm.