Originally Posted by
All Star Superman
A new non-Crisis "crisis" that leads to a bold new direction for DC Comics.
Speedsters throughout the universe are the first to feel it. Something is wrong with time and space. Mystical beings are the next to feel it.
Barry and Wally learn that the merging of the surviving universes at the end of COIE "pulled a thread" in the fabric of existence from the Big Bang to entropy. Each successive cosmic event/Crisis has snagged and snared the thread, pulling on more until finally, all of reality, regardless of plane or frequency, is unraveling.
There is no Big Bad pulling these strings, simply the side-effects of past tampering on the part of super-villains both fictional and real.
The only solution? Separate the post-COIE universe into its five constituent universes, despite the evolution of this universes and the universes/multiverses its spawned.
Long story short, this is achieved through the actions of a collection of characters even greater than the assemblages seen in COIE, though it's Barry Allen's sacrifice that again saves all of reality.
A new, single Multiverse is revealed. Few across this new infinitude remember the events that led to the current status quo.
DC Comics publishes books set on the following Earths, rotating regular series and mini and maxi-series as demanded by sales and fan feedback.
Earth-Zero: Ground Zero for new readers, either an "Ultimate DC" in the vein of Ultimate Marvel and the New 52 or the future of a DCU where the next generation is the focus.
Earth-One: The pre-COIE Earth-One, updated and reset. The Superman/Clark/Lois triangle is still in place, Dick Grayson has just retired as Robin.
Earth-Two: The pre-COIE Earth-Two, updated and reset. Books here are set in the modern era and in the Golden Age.
Earth-Three: The pre-COIE Earth-Three, updated and reset. Books here include a CSA title and The Adventures of Lex Luthor.
Earth-Four: The pre-COIE Earth-Four, updated and reset. The Charlton characters are the focus here, along with a certain time and dimensional traveler with a penchant for the color gold.
Earth-Five: The pre-COIE Earth-Five, updated and reset. Billy Batson utters the magic word "Shazam" and becomes this Earth's greatest and initially, only hero, The World's Mightiest Mortal: CAPTAIN THUNDER.
Earth-Six: The dark home of characters like Swamp Thing, Hellblazer, and others.
Earth-Seven: A world with no superheroes, only sci-fi characters like The Challengers of The Unknown, Adam Strange, and the Thanagarians.
Beyond these universes are others occasionally visited, universes that continue the iterations of the post-COIE Earth as separate universes instead of the heavily-altered New Earth and universe itself.