"The Reign of the Superman" appeared in the January 1933 issue of Shuster's self-published fanzine Science Fiction, because it was easier to name sci-fi magazines back when there were only like four of them. In the story, a mad scientist named Professor Ernest Smalley finds a meteor and devises a way to make it give people telepathic superpowers. Rather than risk it on himself, Smalley naturally decides to test his invention on a random vagrant he finds waiting in a breadline. After a little convincing, Smalley brings the man back to his lab and transforms him into a very super man, who immediately kills Smalley and proceeds to wreak havoc on the world.
Superman initially uses his telepathic powers to thrillingly ... win card games and manipulate the stock market. But if the World Series of Poker has shown us anything, it's that you can only win so many hands of Texas Hold 'Em before inevitably thinking that you deserve to rule the planet. So Superman devises a scheme to disrupt a peace conference and throw the world into chaos, thereby making it easier for him to wrest control from the powers that be.
And then, plot twist, his powers, uh, kind of just fade away. His meteor magic vanishes like he entered the sixth hour of a five-hour energy drink, and since Regular Man didn't think to open a savings account with his blackjack earnings, he simply goes back to standing in the breadline like he was a week ago. The end!
As you might imagine, this D-Tier Twilight Zone potboiler didn't exactly blow up and transform Siegel and Shuster into international literary superstars. But it did make Siegel think, "What if, instead of being a total douche, this awesomely named Superman guy was nice? And maybe he can live in a house?" Then he rolled with the first part but blew up his home planet, because Superman must always be homeless, no matter what.