Radical Highway is Shadow's first stage on the Dark Story in Sonic Adventure 2. This level takes place in an area that resembles San Francisco's Golden Gate Bridge (in the dead of night), which further enhances the "Central City" atmosphere. The theme song of this level is Vengeance is Mine.
Shadow is surrounded by the military and police after stealing the Chaos Emerald from the federal reserve bank. As he watches them, he has a flashback a running down a hallway on the ARK with Maria. Returning back to the present, Shadow promises Maria revenge against humans.
Throughout the stage, there are huge suspension cables of the bridge that Shadow can grind on. Performing tricks perfectly will get you far in this level, as they can allow you to cover great distances and skip large sections. This level has many enemy bots, as well as a few lightning fast (and dangerous) bomber jets.
Level Up Item
Shadow's Flame Ring Level Up Item is found here, he needs the Air Shoes to obtain it easily, but can also reach it without them by using a Spin Dash and jumping at the right moment.
Radical Highway (or somewhere similar) is where the opening cut-scene took place in Sonic Adventure 2.
Radical Highway is filled with snow and used in the Dream Snowboard Cross event in Mario and Sonic at the Olympic Winter Games. Curiously, the NiGHTS cameos in the background were removed and replaced with a neon Chao head. This is probably to keep any non-Sonic or Mario characters out of the game.
A remixed version of the Radical Highway theme appears in the 2P battle mode of Shadow the Hedgehog.
Radical Highway is based off San Francisco's Golden Gate Bridge along with other stages.
By looking at the "Caution!" signs scattered around the level, it's safe to assume that parts of Radical Highway were under construction when Shadow was running through it.
In Sonic Generations, the player plays as Sonic the Hedgehog instead of Shadow. However, Shadow is still present in Radical Highway, as the rival battle takes place there.
The Mario & Sonic incarnation of Radical Highway is the only one to have a different blimp to the others, as the one from Mario & Sonic literally says "Radical Highway" instead of "Got Ring?" or the Soap logo. The NiGHTS cameos are also removed, most likely to keep the represented series to just Mario and Sonic
There is a sign that reads" Time Eater" who is the main villain in the game Sonic Generations. The sign only appears in the Sonic Generations version of the stage.