The main aspect of the gameplay is the ability to have a second character follow you and attack alongside you. The aspect is based off of Sonic the Hedghog 2 and Sonic Advance 3. There are seven playable characters that play similar, but with differences between them. Wisps also return from Sonic Colors, Sonic Generations and Sonic Lost World. The hub worlds from Sonic Adventure and Sonic Unleashed return.
Gameplay on the Wii U is very similar to the daytime levels of Sonic Unleashed, Sonic Colors, and Sonic Generations, changing between 3D and 2D environments. Players can choose to have the gameplay for wisps be similar to Sonic Colors or Sonic Lost World.
Gameplay on the Nintendo 3DS version is a side-scroller similar to the classic and handheld games.
Special Stages appear in both versions. They play similar to the ones from Sonic the Hedgehog 2, Sonic Rush and Sonic the Hedgehog 4: Episode 2. They take place in environments based on the stage.
Each Character plays very similar. The boost gauge now changes depending on the character. Upon completing the game, the characters can use their Super Form, Super Shield, or Burning Form, depending on the player. Characters will play the same, but will be faster and invincible. The form ends after all their rings are drained. During these forms, instrumentals of their theme songs will play.
Sonic's gameplay is basically the same as the previous games. He is available at the start. His theme song is "His World". (The trailer/Smash version is used during the super form). Upon completing the game, Metal Sonic serves as a palette swap by holding the R button when selecting him. His theme song is "What I'm Made Of."
Tails has not homing attack. He instead can use his gauge to fly, allowing the reach of places other characters can't get to. He can also use his tail whip ability from Sonic Adventure. He is available at the start. His theme song is the SA2 version of "Believe in Myself".
Amy plays very similar to Sonic, however she can also use her hammer. The gameplay is slightly similar to Sonic and the Black Knight, although a button is used rather than motion control. She is unlocked upon clearing Green Hill. Her theme song is "My Sweet Passion".
Knuckles has his homing attack replaced with a glide, as well as the ability to climb up walls. His special gauge will activate the Corkscrew ability instead of a dash.. He is unlocked upon clearing Angel Island. His theme song is the SA2 version of "Unknown from M.E.".
Shadow plays very similar to Sonic. His boost gauge is shorter than Sonic's, using less of his Chaos Boost. However, when the gauge is full, it fills a secondary role of freezing both the timer and enemies for 20 seconds. He is unlocked upon completing the Labyrinth Temple. His theme is the Crush 40 vs. Magni-Fi version of "All Hail Shadow".
Silver's gameplay is very similar to Tails (without the Tail Whip). Silver also has the ability to pick up enemies and crates (up to 5 at a time) and throw them at enemies. He is unlocked upon completing the Starlight City. His theme is "Dreams of an Absolution".
Blaze's gameplay is very similar to Knuckles, without the Corkscrew move. Her special gauge allows her to toss fireballs at the enemies. Her theme song is Raisin Me Up, although Velva Nova plays during her Burning Form. She is unlocked after completing the Scrap Brain.
Rouge the Bat appears during the story mode as an ally to Shadow. She and Shadow are looking for the Chaos Emeralds on assignment from G.U.N. Her theme song is "Fly in the Freedom".
Dr. Eggman is one of the main antagonists of the game, and seeks to unleash the Accursed into the World and robotosize it as the ultimate weapon. His theme song is "E.G.G.M.A.N.", and the Robeatnix mix from Shadow the Hedgehog plays during important scenes with him.
Nobody knows what this monstrosity is, except that it can take the form of other mythical beings from memories. It is mindless, allowing it to be captured.
There are eight stages and three hubs. Most can be reached by running through South Island, although Angel Island and the Egg Carrier require the Tornado. The last stage requires the seven Chaos Emeralds. With the exception of the last stage (which is just one boss battle), all hubs contain 4 levels, 2 challenges, a special stage and a boss battle. Some Stages also contain a Rival, which requires three hits.
Hubs and Levels
- Green Hill
- Coastline Jungle
- Labyrinth Temple
- Starlight City
- Scrap Brain
- End of the World
- Angel Island
Egg Carrier mk. 3
- Egg Carrier
Bosses and Rivals
- Metal Sonic (Green Hill Rival) (Sonic CD)
- Egg Robo (Green Hill Boss) (Sonic & Knuckles)
- Accursed 4 (Angel Island) (Sonic Adventure)
- Frigate Orcan (Coastline Jungle) (Sonic Colors)
- Shadow (Labyrinth Temple Rival) (Sonic Adventure 2)
- King Boom Accursed (Labyrinth Temple Boss) (Sonic Adventure 2)
- Egg Hawk (Starlight City) (Sonic Heroes)
- Blaze (Scrap Brain Rival) (Sonic Rush)
- Accursed Ifrit (Scrap Brain Boss) (Sonic Rivals 2))
- Egg Viper (Egg Carrier) (Sonic Adventure)
- Perfect Accursed (End of the World) (Sonic Unleahsed)
After going through Green Hill Zone, Sonic and Tails see their archenemy, Dr. Eggman, looking for Chaos Emeralds. The two chase after him. They run into Metal Sonic and destroy him. The keep looking until Dr. Eggman notices them. He sends in a giant Egg Robo and Eggman flees to find the Chaos Emerald. Sonic and Tails manage to defeat the Robot, as it explodes. The two see Amy lying in the ground. Sonic tries to wake her up. He is successful and she explains that Dr. Eggman kidnapped her to use as a power source for his robot. Tails says he has Dr. Eggman on radar. He is heading to Angel Island. The three could get there, but he needs a Chaos Emerald to power his tornado. The three eventually find one and take off.
The three land on Angel Island, ready to find Dr. Eggman. They eventually reach the ruins that hold the Master Emerald. They find Dr. Eggman and a KOd Knuckles. Eggman uses the six Chaos Emeralds he has and reveals he found the seventh in Tails plane. He then uses a mind control cannon filled with Wisp energy to get Knuckles to empower the emeralds. He is succesful, and a portal appears in the sky. Out comes a tiny cloud that gets on Sonic's face. It then jumps off and turns into a form resembling Chaos 4. The seven Chaos Emeralds scatter, and Eggman leaves, declaring he'll come back to robotosize the creature when he destroyed the team. Sonic and the gang manage to defeat it, causing it to fly away in a weakened form. Knuckles wakes up ready to get revenge. Sonic and the others manage to find one of the Chaos Emeralds on the island and leave. The team of four then go through other zones, find the Chaos Emeralds along the way.
They land in a Jungle, ready to advance to Dr. Eggman's base, the Scrap Brain Zone. They make it through until they find the Frigate Orcan above them. The team manage to destroy it, but it starts to crash. The four run into a temple for shelter from the explosion, but are now trapped.
They eventually run into Shadow and Rouge, who demandd the Chaos Emeralds the group have. Sonic manages to best him, and Shadow insists he give the emeralds for G.U.N., so that they can destroy the strange beast that has arisen. Amy asks the two if they could work with the group to stop the creature and find the other emeralds. Both Sonic and Shadow are hesitant at first, but agree. They go through the temple trying to find a way out. They find a mural with the creature destroying the world and seven figures of light destroying it. They see an alter meant to worship the creature, when the same creature appears and gains power from it. It jumps to Knuckles and turns into a creature resembling King Boom Boo. After stopping the creature again, it suddenly is getting a reading from a Sonar. It destroys a wall, allowing the group to escape.
They run into Starlight City, ready to get to Eggman's lair. They run into the Egg Hawk, piloted by an Egg Robo. After causing it to Crash into the ocean, a portal opens up and Silver jumps throuIngefr with a body. He explains he's come back to the past to stop a creature known as the Accursed from destroying the world. Knowing its the same as the creature, they team up.
They make it to the Scrap Brain, and after making it through the industrial area, they find a captured Blaze, with a visibly upset Silver. Eggman says that the Accursed will be stronger upon possessin\g a body and attaches it to Blaze, forcing the group to have to knock her out. As she is unconcious, the creature escapes, turning into a form resembling the Ifrit. They finally stop it, and it explodes. Blaze wakes up, ready to get revenge on Eggman. He flees in his new Egg Carrier. Blaze explains that the Sol Emeralds lose their power every 1000 years and require the counterparts of another dimension to be recharged. The eight go back to the Jungle, jump into the Tornado and take off.
Eggman attempts to destroy South Island as revenge, using a Chaos Emerald as the power source. The seven go through the Egg Carrier and steal the Chaos Emerald. The Egg Carrier starts falling and Eggman insists that no matter what, he would destroy Sonic. He jumps into the Egg Viper ready to destroy the group, but is stopped by the seven. The Egg Carrier crashes into the ocean as the seven escape in the tornado. Upon reaching Green Hill Zone, Blaze explains that the Sol Emeralds lose their power every 1000 years and require the counterparts of another dimension to be recharged, so the team agree to find all the Chaos Emeralds to help Blaze.
After empowering the seven Sol Emeralds, Blaze is ready to go home, when a small little black bug rests on a Sol Emerald. It takes the power of the Sol Emerald and becomes completely empowered. It takes the memories of Sonic and becomes a form resembling Perfect Dark Gaia. The group (minus Rouge) agree that they know who the golden figures in the Mural were. The seven Chaos Emeralds surround Sonic, as the Sol Emeralds surround Blaze. They turn into Super Sonic and Super Blaze, as Super Sonic shares his power with the rest of them. They fly up to the Accursed ready to destroy it.
The seven succeed, causing it to explode. With that, Shadow and Rouge take the Emeralds to G.U.N., Blaze returns to her dimension, Silver returns to the Future, Knuckles returns to Angel Island, and the rest of them head to Tails' Workshop to celebrate.
In a post-credits scene, the Accursed is revealed alive as a bug, when it is confronted by Dr. Eggman. Furious it couldn't destroy Sonic, he crushes it. With its last dying Breath, it breathes fire at the Doctor's mustache, burning it all off.
The game is compatible with amiibo, giving costumes to Sonic based off of previous Crossovers with Mario, Yoshi, Link and Mega Man. Tapping the Sonic amiibo unlocks Sonic Adventure on the Wii U version and Sonic Advance on the Nintendo 3DS version.