"Across the multiverse, Sonic the Hedgehog has fought the Mad Doctor. But now, from the ashes of past defeats, the city of Egg-O-Tropolis stands high, with a mysterious and new asset at the center of the Mad Doctors' plans. To lead the Sonics to them? A grim warning... a mysterious message... a path home... all of them lead to the Genesis Nexus... all of them lead to the ultimate Terminus."