When an era finishes, there will be a time skip of perhaps a few decades. For many characters, that would leave them still functional. Some superheroes might retire or have passed on. You might be playing their 'grown up' sidekicks and proteges. Alternately you might be playing an entirely new character.
Example: Superman has stayed more-or-less the same through all the eras of comic book history.
Captain America stayed the same for awhile, but at some point retired and passed on the shield to another Captain America who had different powers.
The story will begin in the Golden Age. You will be Allied Mystery Men fighting Nazis.
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link to another game