I actually was in an Alpha-test for this games. I was visiting Austin TX around 1982 and called to see if I could visit Steve Jackson games. And they needed people to test a new game. They dropped a couple of the ideas. But it was released not too long after.
Illuminati: The Game of Conspiracy
Steve Jackson games most famous game was Car Wars, based on the book, "Why Johnny can't speed", by Alan Dean Foster of Star Trek fame.