Returning from Sonic the Hedgehog (2006), Aquatic Base houses moving platforms, water tanks, and lots of enemies. A new area, a cave under the mansion, is added with traps to avoid and puzzles to solve. Sonic has to fight ghost to proceed though the mystic rooms and light lanterns to reach the goal guarded by ghosts. Ghosts sometimes chase Sonic though the stage.В In Act 1, ClassicВ Sonic must collect three Master Emerald shards before reaching the goal. Sonic must run across bridges connecting from giant pumpkin to pumpkin. There a beautiful sights, but just watch out for hazards. Windy Valley takes place inside of a tornado, a field, and a race track in the sky. In Act 1, Classic Sonic has to climb up the summit and defeat the mini-boss from the original game. Sonic can snowboard down the mountain and defeat enemies as he makes his way to the goal. Ice Cap is a steep mountain from Sonic the Hedgehog 3. However, an earthquake occurs in Act 2, causing Modern Sonic to fall into a cave. Much like in the first stage from Sonic the Hedgehog 2, Sonic must avoid bottomless pits, enemies, and spikes. A new section above the undergrounds has been added. No lava appears, and secret passageways scatter the course. This stage has been made easier from Sonic the Hedgehog. Eggmans are in an after-credits scene and get in a humorous argument.

Chaos: Chaos has been angered by Metal Sonic, who has sent him back in time to distract Sonic.

Jet the Hawk: Like Rouge and Espio, Jet is a fake created by Metal, and is sent to defeat Sonic in the Wii U version.

Mecha Sonic: Mecha was rebuilt by Metal Sonic, and is sent to defeat Sonic in the 3DS version.Rouge the Bat: Rouge challenges Sonic, but it is later revealed it was a fake created by Metal Sonic.The player cannot use Metal Sonic, however, but plans for him to be playable was a beta element. Metal Sonic: Metal Sonic brought Sonic into this world in an evil plot to destroy him.Miles 'Tails' Prower: Tails assists Sonic in escaping the grey world, and tells helpful tips to the player.

Sally Acorn: Sally is the beautiful princess acorn and she's with Sonic's love intrested.

Super Sonic has a Spin Dash, a Boost, and a Homing Attack.

Super Sonic: Super Sonic is actually Sonic once he is using the positive energy of the Chaos Emeralds.

Classic Sonic has a Spin Dash and a Stomp, while Modern Sonic has a Boost, a Homing Attack, a Drift, and a Slide.

Sonic the Hedgehog: Sonic is the playable character, who is gifted with extreme speeds and tall jumps.

The robot is defeated, and the three Sonic go back to their own worlds. It is revealed that an unknown villain has brought them to this world, and that they must get back to their own world.В The three SonicsВ collects the Chaos Emeralds from the bosses, then sees the mastermind of this plot, Metal Sonic.В Metal uses the negative energy of the emeralds to transform into a super form, and the two Sonics follow him as Super Sonic. Meanwhile, the modern Sonic with Tails help eggman evil plan, and black hole sucks them into the same grey world.

Meanwhile, Classic Sonic runs though Station Square, olderВ then when he was in Sonic Generations, and suddenly a black hole sucks everything into a land of grey. Some noises are heard as a red eye glows in the room.

Sonic generations character mods