When the Deadly Six threaten to destroy his world, Sonic’s new moves & power-ups are the only way to defeat them before it’s too late! This is the first out of the three titles of Sega and Nintendo's exclusive collaboration, the others being Mario & Sonic at the Sochi 2014 Olympic Winter Games and Sonic Boom: Rise of Lyric/Sonic Boom: Shattered Crystal.

Sonic the Hedgehog and his best friend Tails are hot on the trail of the villainous Doctor Eggman, who has captured a host of their animal friends to power his ever-growing robot army. During the pursuit, Eggman shoots down Tails' plane, and the two heroes crash-land in a strange new world floating in the sky known as the Lost Hex. As they explore this uncharted realm, they discover that Eggman has enlisted the aid of the Deadly Six, a group of the world's native Zeti creatures, keeping them obedient with a magical conch. When Sonic impulsively kicks the conch away, the Deadly Six turn against Eggman and seize control of his robotic forces, setting in motion a new and dangerous threat that forces old enemies into an uneasy alliance.