Wow, Robert Anton Wilson. There's an author I haven't thought of in a very long time. I was very taken by his books and read them all. They had a "sci-fi adjacent" feel to them.
His best-known volumes are "The Illuminatus! Trilogy" (1975). Which is where I came across him.
Advertised as "a fairy tale for paranoids," the three books "The Eye in the Pyramid, The Golden Apple, and Leviathan" were a huge "mindfuck "Hero's Journey". Through an alternate reality where basically ALL conspiracy theories were true.
There was a movie a few years before that really captures the bizarre yet fascinating appeal of Wilson's books. "The Final Programme" (1973) was about,
A trio of scientists plan to create a self-replicating, immortal, hermaphrodite using the Final Programme developed by a dead, Nobel Prize-winning scientist.
It gets crazier from there. I remember Wilson's books being like that. Absurdist and deep at the same time.
Wikipedia says his works examined, among many other themes,
"occult and magical symbolism and history, the counterculture of the 1960s, secret societies, data concerning author H. P. Lovecraft and author and occultist Aleister Crowley, and American paranoia about conspiracies and conspiracy theories.
The books mixed true information with imaginative fiction to engage the reader in what Wilson called "guerrilla ontology", which he apparently referred to as "Operation Mindfuck" in Illuminatus!
The trilogy also outlined a set of libertarian and anarchist axioms known as Celine's laws (named after Hagbard Celine, a character in Illuminatus!), concepts Wilson revisited several times in other writings."
That sounds about like I remember. There was also a very Douglas Adams "Hitchhikers Guide" sort of humor to them.
I also read his Schrodinger's Cat Trilogy.
The Universe Next Door, The Trick Top Hat, and The Homing Pigeons.
Wilson set the three books in differing alternative universes, and most of the characters remain almost the same but may have different names, careers and background stories. The books cover the fields of quantum mechanics and the varied philosophies and explanations that exist within the science.
I found it extremely interesting. He had a very unconventional way of looking at things. I also listened to him speak on several panels at sci-fi cons. For a lot of us in that time period he was the Hunter S Thompson of sci-fi.