Take a gander at this:

Francesco Francavilla's 1935 Batman

If I was going to run a super-hero RPG right now, first thing I’d do is gather those folks together and have every bring a pile of comics and/or trade paperbacks.  Single issues would probably be better.  I like the idea of them scattered all over the game table.

The world is every world.  Every comic book that ever happened, happened.  The comic book heroes are as old right now as if they had started on the day their first issue came out.  We’d figure out amongst ourselves what that meant.  It is the Silver Age taking to its illogical conclusion.

“I want to play the child of Batman and Wonder Woman, a grim little girl raised on Themiscrya who went to a Gotham Prep school for her teen years.”

“But I want to play the adopted child of Batman and Superman raised in Metropolis!”

“Why can’t both exist?  You’re siblings in DC’s own Trinity Family.  As a matter of fact, that is looking like what this game is going to be about, the most powerful family in the world.”

“Can my Amazonian Gothamite be engaged to Franklin Richards?”

“Yes, you can.”