Yeah! Here's a little blurb from Wikipedia detailing his original concept of the ride:
As an original story was developed,
George Lucas was brought in to work on the project. This version's storyline had X-S Tech's open house being a front for exposing human guinea pigs to an alien monster they had captured. After the alien menaces the audience for a moment, it is revealed to be sentient and desires to escape its captors and free the guests as well. The X-S scientists respond by trying to destroy the test chamber and leave no evidence, but the alien holds off their weaponry, raises the restraints allowing the guests to escape. While leaving, the sounds of the alien rampaging through the pre-show facilities could be heard. The story's grim tone would lead to it being further re-worked.