The story starts in the Sonic Boom Timeline, where Time Eater attacks, and opens portals. The 5 Heroes are trapped inside 5 ones, but Tails was sent to Modern Sonic's Timeline.
Modern Sonic finds Boom Tails, thinking he is the real Tails. Boom Tails thinks Modern Sonic is the Sonic from his dimension. Suddenly, Time Eater opens another Portal, sending Sonic and Tails to a new version of the void HUB from Sonic Generations. The first stage is Green Hill Zone, which has no boss fight. After cleared with both characters, it skips to a cutscene were Sonic finds Modern Tails. He then learns from the two Tails that Time Eater brought the other Tails from another timeline. Afterwards, after saving Tails, Underground Zone appears. The heroes head to it.
After defeating Arjiigoku Mech, Classic Sonic and Classic Tails are found. At this point in the game, you don't have to clear every single stage in the zones with all characters. After clearing Aquatic Army Zone, the heroes are transported to the Death Egg, where you must battle Death Egg Robot.
After his defeat, it skips to a cutscene in the Modern Death Egg. Zavok appears, as he has once again formed a alliance with Eggman. Robotnik and Lyric are also there, and the rest of the Deadly Six. Zavok sends the Deadly Six to go find Sonic and co.
The heroes find Classic Knuckles at Angel Island from Sonic 3. Nack comes and uses his mech to snatch the Master Emerald. Classic Knuckles joins the heroes for now to go get the Master Emerald back.
Classic Knuckles returns the Master Emerald to it's place. But he attacks Classic Sonic. Classic Sonic runs away, and ends up in Hidden Palace Zone. He has to find his way out in this 1 level zone, and battle Classic Knuckles at the end.
|Image||Information and Controls|
|Modern Sonic is a very fast character. He can spindash, and do Homing Attacks. With the 7 Chaos Emeralds, he can become Super Sonic. He can also do a speed dash, on ground or air which hits foes infront of him, or makes him faster.|
|Tails can fly, and use a ray gun he built to destroy enemies. He can also stun enemies with it, or inflict damage on boss fights. He can preform a spindash also, and turn into Super Tails.|
|Knuckles can destroy big rocks, and smash through some places featured in only his levels. He can turn into Hyper Knuckles, and use melee attacks to hit enemies. He can also glide and climb walls.|
|Amy can use her hammer to harm enemies. She can't spindash, however. She can use her hammer in air, and give herself a boost by using a spin attack with it.|
|Classic Sonic can do the same stuff Sonic can, but he can't homing attack. He can turn into Super Sonic also, and has shields he can use, unlike Modern.|
|Classic Tails can fly higher then Modern and move faster, due to him being lighter. He can't use a ray gun through.|
|Classic Knuckles is weaker then Modern Knuckles, but Classic can glide and climb walls much better then Modern. He can also turn into Hyper Knuckles.|
|Classic Amy can jump higher, and hit slightly harder then Modern Amy, but she has terrible hammer spin ability. She can preform a jump and slam move through.|
|Boom Sonic can use his beam to get to other places, and use the same moves as Modern Sonic. All Sonic Boom characters cannot go super, due to there being no Emeralds in there dimension.|
|Boom Tails can fly, but can't use a ray gun. Instead, he can build mini versions of the Tornado that can fly into enemies, or shoot missiles. They can be easily destroyed.|
|Boom Knuckles can dig underground, and break rocks and hard objects. He is a melee fighter too, and the strongest character in the game.|
|Coming Soon||Coming Soon|
|Green Hill Zone||Classic||In the start of the game, Modern Sonic and Boom Tails are sent to Green Hill Zone. This is the 2nd smallest area in the game, only having 2 Levels.||None|
|Classic||After recruiting Modern Tails, Underground Zone appeared. Once cleared with the 3 characters, a 4th level with the battle with Arjiigoku Mecha appears.||Arjiigoku Mecha|
|Aquatic Ruin Zone||Classic||Aquatic Ruin Zone is found after getting the two original classics on the team. After completed with 4 characters, the heroes are taken to the Death Egg, where Death Egg Robot appears!||Death Egg Robot|
|Angel Island||Classic||Classic Knuckles appears. Nack steals the Master Emerald, so Classic Knuckles joins the heroes to go get it back.||Nack the Weasal|
|Hidden Palace Zone||Classic||Classic Sonic is the only playable character in this one. It's one zone also. A battle with Classic Knuckles!||Classic Knuckles|