Worlds Unite

Worlds Unite is a crossover between the Sonic the Hedgehog and Mega Man comic franchises published by Archie Comics. It is the second crossover between the Sonic the Hedgehog and Mega Man comic series, the first being in 2013 with Sonic &amp; Mega Man: When Worlds Collide. It was released on Spring 2015. Mega Man's and Sonic's portion of the storyline take place during the present time of their comic storyline, while the Mega Man X's portion of the storyline take place during an indetermined point between Mega Man X7 and Mega Man X8.

Development
The premise had earlier been foreshadowed in the Off-Panel strip in the first issue of Sonic the Hedgehog since the Worlds Collide crossover's end, where Sonic, after returning to his story, discovers the dreary events of what was occurring, and made plans to stay at Mega Man's place for "the next crossover." The crossover was also hinted at in Mega Man issue 43, when Xander Payne, while insanely ranting about the future he saw and etching his visions onto his cell wall with a makeshift shiv, ominously states that "worlds will collide again." It was later confirmed that the Mega Man X and Sonic Boom universes would also be involved.

In the lead up to the crossover's premiere, the various Archie Comics franchises that are connected to the crossover had a countdown on the cover listing how many issues it has before it enters the crossover: issue 47 of the Mega Man franchise was three issues before the start of the crossover, while the various Sonic series (Sonic Boom issue 6, Sonic the Hedgehog issue 271, and Sonic Universe issue 74) were two issues before the start of the crossover.

Like in the previous crossover, the story was written by Ian Flynn and all cover artwork for the issues partaking within the crossover was drawn by Patrick "Spaz" Spaziante. According to Paul Kaminski:

"When the worlds of Sonic the Hedgehog and Mega Man collided in the pages of Archie Action comics, readers, fans and retailers made it the biggest crossover event in Archie Action history. That historic crossover storyline changed the comic book worlds of Sega and Capcom's iconic video game characters forever, but now an even bigger event is on the horizon. You saw what happened when worlds collided, now see what happens when Worlds Unite! And this time, no universe will be safe..."

On December 12, 2014, a teaser poster was unveiled revealing Mega Man X and Sticks the Badger encountering each other, indicating that, in addition to the standard Mega Man and Sonic the Hedgehog/Sonic Universe series, the Sonic Boom and Mega Man X universes at least will collide with each other as well. Paul Kaminski quoted:

"Not one, but TWO new casts will be joining the battle in this summer's Sonic/Mega Man WORLDS UNITE crossover event! The worlds of Sonic Boom and Mega Man X will be joining the fray, accompanying the worlds of Sonic the Hedgehog and Mega Man in the biggest crossover event in Archie Action history! The Sonic Boom comic series is part of the latest multi-media initiative from Sega, which includes video games, toys, and an all-new TV series on Cartoon Network! Mega Man X has been a staple of video game culture for decades, and we were thrilled to begin exploring that futuristic universe in 2014's Dawn of X storyline in the Mega Man comics! How will the slapstick antics of the ever-paranoid Sticks the Badger measure up against the futuristic action of X and the Maverick Hunters? Pick up Worlds Unite, starting this spring from Archie Action, to find out! And this is only the tip of the iceberg…"

In 2015, it was revealed that more universes from Capcom and Sega franchises would appear in the crossover. In large part because of this, there would also be two Battle Books in addition to the 12 main issues in Worlds Unite, to ensure all characters are used to some capacity.

Issue List
(Ian Flynn confirmed that the order of the Sonic comics prior to Worlds Unite from the Free Comic Book Day story to Sonic Universe occurred in the order listed)

Trivia

 * Worlds Unite essentially serves as the Archie Comics adaptation of Sonic Lost World. The basic setting and plot points (Eggman trying to use and losing control of the Deadly Six and draining life from the world for the villains to power themselves up) are carried over, only with Sigma as the instigator of the plot and the one siphoning the power of the world instead of the Deadly Six.
 * The use of other Sega and Capcom characters also harkens to the Project X Zone series, except for the fact no Namco Bandai characters are featured.
 * Out of all series represented in the crossover, only Street Fighter has its own ongoing comic series, with UDON Entertainment allowing the use of the characters.