This stage is set within Metropolis, Dr. Eggman's city, which is a magnificent white city, filled with skyscrapers and brimming with technology. During the events of the game, the Resistance launched an attack on Metropolitan Highway after they thought they had disabled the Phantom Ruby.
Metropolitan Highway is located within Metropolis which appears as a magnificent and pristine, but sterile white city where geometric shapes appear to be a recurring architectural theme. It features multiple skyscrapers in various designs, numerous large-scale video screens, and open, see-through highways, all of which look like they are taken straight out of the future. Various buildings with advanced technology fill the city as well. There are also orb-shaped sentries inside the structures and hover cars that fly between the buildings. In addition, the sky above Metropolitan Highway is free of pollution; instead, it is blue with a couple of clouds dotting it. Resistance airships can also be seen engaging the Eggman Fleet in the sky.
The bottom of Metropolitan Highway is not visible; the entire ground level below the skyscrapers is obscured from view by a thick cloud cover. Also, Metropolitan Highway has no traces of organic nature. Instead, it has metallic mimics of trees and bushes along the roads.
The stage primarily takes place on the rooftops and highways of the city, with some sections taking place within the buildings themselves.
After the destruction of the Death Egg, the Resistance's believes the Eggman Empire's secret weapon―the Phantom Ruby―to be harmless, now with its power source gone. With an opening now available to them, the Resistance attempts another attack on Metropolis in hopes of winning the war to take back the planet.
Once Sonic enters the city, he is tasked by Knuckles to find Dr. Eggman and capture him to allow the Resistance to win. Amidst the attack, Knuckles and Rouge promise Sonic cover support, while Amy leads him toward the doctor. Eventually, Sonic and Tails find Eggman, Orbot and Cubot. However, rather than surrendering, a confident Eggman calls in Infinite and has him create a portal into Null Space with his Phantom Ruby prototype's power.
As Sonic gets pulled into the portal, the Avatar shows up and attempts to rescue him, only to get pulled into Null Space with him. After the portal closes, Tails is left bewildered by this turn of events, as the Phantom Ruby should be powerless. It is then that Eggman returns and gloats that he has learned from his mistakes: instead of having just one power source as usual, he built a back-up power source for the Phantom Ruby under Metropolis.
Metropolitan Highway has several small platforms that move quickly in one direction the instant Sonic sets his feet on them. The direction in which these plaforms move is indicated by the green arrows on the side of said platforms. While the platforms sometimes help the player cross gaps, they can also be traps that can lead Sonic into walls with spikes that can knock him into bottomless pits.
The stage starts out with a 2.5D section inside a multi-storey building. Begin by following the paths on the right. Along the way, there will be spiraling Grind Rails and the stage's fast-moving platforms. At the end of the 2.5D section, Sonic will enter a 3D section before getting launched into midair by a Spring. Sonic will then enter a skydiving section while missiles are being fired at him from a launch pad directly below him. Avoid these missiles, and follow the highway in front of Sonic after he lands. Along this highway, there will be Egg Walkers that will run from Sonic while firing missiles at him.
Eventually, the player will enter another 2.5D section. This section makes significant usage of the stage's fast-moving platforms, which the player is obligated to use to advance, despite some of them having been set to serve as traps as well. After leaving this section, the player will enter a 3D section where they run down a highway with more Egg Walkers. At the end of this highway, the player is sent flying towards the goal, which is situated on the roof of one of the buildings.
|"Metropolitan Highway"||Tomoya Ohtani||2:56|