The world of Sonic the Hedgehog hasn't always been the simplest to understand. If the original 2D games were anything to go by, then one could be forgiven for believing that Sonic's world was filled with cute little forest creatures, anthropomorphized animals, and only one human in the form of Dr. Robotnik. Then when Sonic committed to 3D games with Sonic Adventure, suddenly things changed and the Blue Blur lived in a world much more like our own. What fans of the beloved video game series may not know is that Sonic's comic book adventures linked all the games with a horrifying post-apocalyptic secret.
This haunting truth was revealed in the Sonic Adventure 2 sequel storyline "Sonic Adventure 2.5," which took place during Archie Comics' Sonic the Hedgehog #124 and #125 by Karl Bollers, Dave Manak, Art Mawhinney, Ron Lim, Dawn Best, J. Axer, Steven Butler, Conor Tomas, Andrew Pepoy, Pam Eklund, Nelson Ribeiro, Josh Ray, Aimee Ray, Jim Amash, Jason Jensen and Jeff Powell.
The story picks up straight after Shadow's heroic sacrifice at the end of Sonic Adventure 2. As the Ultimate Lifeform falls to the planet below, he is saved from certain doom by alien lifeforms called the Blem. They send Shadow to fight off an alien invasion that threatens all of Mobius, Sonic's homeworld. His failure to stop them here leads to a stunning revelation as to why the invaders have come to Mobius.
This hostile species, the Xorda, attacked the human population of Station Square as well as Eggman's own mechanical empire. After their display of force, the entire planet Mobius receives a telepathic message explaining why they've come with such a vengeance.
Thousands of years earlier, the Xorda came to Earth to seek an alliance with humanity. However, their peaceful emissary was met with hostility, and the humans who met the Xorda were imprisoned and dissected it. In response to such a horrible welcome, the alien species eradicated all life from Earth's surface using gene bombs. Now, having seen that their vengeful purge failed, they have returned to finish the job.
This tale left Sonic and his friends very confused. If the Xorda were looking for Earth, why did they come to Mobius? Sally, having conducted her own research after hearing the Xorda's story, breaks the news that the invaders are not mistaken - Earth and Mobius are one and the same.
Though some humans survived the purge, they were no longer the dominant lifeforms. The Xorda's gene-bombs had the unintended consequence of mutating the planet's lower lifeforms, creating mobosapians. So not only is the world that Sonic runs around in the post-apocalyptic remains of Earth, he and his friends were created by the very weapon that brought humanity to the brink of extinction.
This messed up origin story for Sonic's home planet of Mobius is only one version of events though. The Archie Comics had their own take on Sonic's continuity, mixing elements and characters from the American Sonic the Hedgehog cartoon show with the games as they released. Reboots such as Archie Comics' Super Genesis Wave and IDW's Sonic the Hedgehog series, as well as the games having their own explanations for events, means that this apocalyptic origin isn't exactly canon anymore. Even still, it's bizarre to think that one version of Sonic the Hedgehog exists thanks to Earth's apocalyptic fate.