Earth-54
This world is inhabited with superhumans but unlike the others this one has something the others don't.
When they first showed up is a mystery though with people like Johnny Lightfoot we can assume they've been around since the Wild West they just tried to keep their activities a secret.
The first "open" superhero came shortly after WWI and called himself Air Ace, this inspired many others to join the fight against injustice.
In the 40s a hero called Astro-Naut gave his life to save a city named Romeyn Falls from an as of yet unknown threat. The city was renamed Astro City in his honor.
Astro would later turn into the city that had the most superheroes the most powerful hero that ever resided there was a man named the Samaritan.
From what we gather he used to live in a desolate alternate future where the world was a barren wasteland as a last resort a man was sent back in time to change history.
On his way to 1980s he got immersed in the time field and gained incredible powers, he was so fascinated by these he almost forgot about the event he was supposed to fix (the Challenger Space Shuttle disaster.)
The 70s and 80s were home to "The Dark age" a terrifying place filled with intense gang and superhuman violence.
One notable feature about this Earth is that the superhumans here act more human then other ones. One does not know how to describe this save that superhumans do not seem as inhuman as other ones…like their just normal people rather then wielders of incredible power.
Dr. believes that this world while not as heavily superhuman populated as his Earth is probably going to be a hard conquest. And since he might have an easier time if they don't know about his plans as th cells there deal simply in genetic research rather then terrorist attacks.