In the late 1970s, Toho was looking to revive the Godzilla franchise. Looking for fresh ideas for future films, longtime Godzilla producer Tomoyuki Tanaka commissioned several prominent Japanese science fiction authors to write their own takes on Godzilla. One of these authors was Yoshio Aramaki (probably best known in the West for his Konpeki no Kantai series, an alternate history revolving around a victorious Imperial Japanese Navy in WW2). In April of 1979, Aramaki submitted a story treatment known as either God's Godzilla or Godzilla: God's Angry Messenger. A translated version of Aramaki's original story treatment is now on the main site for anyone who wishes to read it; it's fairly "out there" for a Godzilla film.
One thing I find interesting about this draft is that despite Godzilla's unusual origins and depiction is that in terms of symbolism he does return to his nuclear roots, in a fashion. He is unleashed by the aliens to punish humanity for their warlike ways as a crisis in the Middle East is on the verge of escalating into WW3; at the time Aramaki wrote his treatment (1979) Cold War tensions were beginning to mount as US-USSR detente fell apart, with a number of crises in the Middle East (most prominently the ongoing Iranian Revolution and the outbreak of civil war in communist Afghanistan that would lead to Soviet intervention later that year) serving as prominent flashpoints. The energy crisis that starts the war, too, is clearly drawn from the real-life oil crises of the 1970s (the first a result of the Yom Kippur War in 1973, the second being as a result of the aforementioned revolution in Iran).