After Classic Sonic celebrates his 20th birthday with Modern Sonic and friends, Classic Sonic and Classic Tails jump into a portal which leads them into the Void. Both era’s Eggmans are stuck in the White Space, however, they accidentally stumble upon an opening to the Void, seeing Classic Sonic and Tails soaring across. The Eggmans fire their laser pistols through the opening, hoping to hit Sonic and Tails, but their attempt failed and hits the Void. The Void then becomes highly aggravated and unstable, which splits Sonic and Tails up and sends them to their own time. However, expecting to return to his own time, Sonic ends up to what seems to be Green Hill Zone, but he could see that something was wrong. Green Hill Zone has transformed into a place called Midnight Aurora Zone. Due to the disturbance in the Void, the Time Continuum for Sonic has been completely distorted. Sonic thinks that maybe collecting all 6 Chaos Emeralds will restore the Time Continuum, but he does also notice that all these events involving travelling through generations and the Time Eater seem oddly connected in a diabolical way… Game is hard.