On Monday, Marvel released an Adi Granov-illustrated teaser for "Civil War" in summer 2015 -- with the familiar imagery and logo of the publisher's massively successful 2006-2007 event series. No further details were released, leading observers to speculate on what it might be. (A tie-in to the recently announced new "Secret Wars"? A new collection of the original material? Something else entirely?)

That was conspicuous enough, and then on Tuesday, Marvel followed up with a teaser for "Age of Ultron vs. Marvel Zombies" in summer 2015, pitting the 2013 Brian Michael Bendis-written time-travel event against the series of miniseries initially launched in 2005 by "The Walking Dead" Creator Robert Kirkman and artist Sean Phillips and things got even more head-scratchy.

Today, CBR has the exclusive first look at Marvel's latest teaser: "Years of Future Past," as drawn by celebrated veteran artist Arthur Adams and also tied to summer 2015. Clearly, it's a reference to legendary X-Men two-part arc "Days of Future Past," which inspired this summer's "X-Men: Days of Future Past" feature film. The imagery reflects the original story's 1981 setting, with a classic X-Men team on one side, the Brotherhood of the Mutants on the other, and Sentinels, Kitty Pryde and her time-displaced adult self in the middle.

What does this all mean? Well, it's still up in the air, but more teasers are likely to surface. "Atlantis Attacks House of M" or "Secret Onslaught Invasion" just might be next.

Keep reading CBR for the very latest on these mysterious Marvel teasers.