Here's the 8-page story:
From Wikipedia: Until Mad #4, the magazine had not been one of EC's top-selling
titles, but "Superduperman" revolutionized their format and led to sales
success. In his book Comics, Manga, and Graphic Novels: A History of Graphic Narratives, Robert Petersen observes, "In April 1953, Mad #4 included a parody of Superman,
'Superduperman,' which originated a new formula that would
significantly raise the popularity of the new magazine. Instead of
broadly lampooning a genre of comics, 'Superduperman' levelled its
sights on a specific and recognizable comic character." National, the owners of Superman's copyright, threatened to file a
lawsuit over the parody. EC and National shared the same lawyer, who
advised Gaines to quit publishing parodies. While Gaines was weighing
this advice, Kurtzman located a legal precedent that backed his and Mad's
right to publish. Gaines hired the author of that precedent to write a
brief substantiating EC's position, but the companies' shared lawyer
disagreed, siding with National over EC. Gaines consulted a third
lawyer, who advised Gaines to simply ignore the threat and continue
publishing parodies. National never filed suit, and this legal cover establishing the basis for Kurtzman's new editorial direction became the bedrock of Mad's humor.
Most likely, Image/Extreme/Maximum would have used this parody protection should DC have sued them over all the Superman similarities in Supreme. Of course, DC had other ideas in mind, but I'll get to that much later.
The important part is the significance Superduperman had on a young Alan Moore:
"I remember being so knocked out by the 'Superduperman' story that I immediately began thinking – I was 11, remember, so this would have been purely a comics strip for my own fun – but I thought maybe I could do a parody story about Marvelman. This thing is fair game to my 11-year-old mind. I wanted to do a super-hero parody story that was as funny as 'Superduperman,' but I thought it would be better if I did it about an English superhero."
That was the genesis for Marvelman/Miracleman. Eventually, it would lead to Watchmen, too: "We wanted to take Superduperman 180 degrees – dramatic, instead of comedic."
The idea of using his own imagination to create stories, even for characters that were already being published. It was a magical idea!
