In Act One, Classic Sonic will have to roll under barrels, bounce over G.U.N. Beetles, swing through bars as well as having to catch the "Got Ring?" blimp in time. There are also G.U.N. planes chasing him down, but he can still attack them. The stage has a lot of slopes, so Sonic can gain speed quite quickly by rolling through them.
In Act Two, Modern Sonic runs across buildings, grinds on the rails of the bridges, and dodges G.U.N. Planes. The level is designed in a some-what 3D environment where some routes are in between others, so depending on what Sonic does, he will end up in either the foreground grinding on the bridges, the middleground going through middle of the bridge or going into the background to avoid a platforming section. There are also hidden rockets that Sonic can find if he jumps at the right time which allow him to skip some areas.
Die-Hard: Clear Radical Highway in 3:00.00 without losing a life!
Ring Collector: Collect 30 rings in Radical Highway in 1:00.00!
Keep the Pace: Grab Time Items and clear Radical Highway in time!
Rampage!: Defeat 11 enemies in Radical Highway in 0:45.00!
Stealth Attack: Clear Radical Highway in 3:30.00 without defeating enemies!
Special Trial: Defeat 3 Gold Beetles in Radical Highway in 2:30.00!
Perfection: Clear Radical Highway in 5:00.00 without taking damage!
Ring Collector: Collect 75 Rings in Radical Highway in 1:00.00!
Keep The Pace: Grab Time Items and clear Radical Highway in time!
Rampage!: Defeat 15 enemies in Radical Highway in 0:30.00!
Stealth Attack: Clear Radical Highway in 0:40.00 without defeating enemies!
Item Collector: Get all Item Boxes in Radical Highway in 1:30.00!
Special Trial: Boost through Radical Highway in 5:00.00!
0:00.00 - 2:00.00
0:00.00 - 3:00.00
The music of the stage is a remix of Vengeance is Mine. The remix has been praised vocals that are easier to understand than the original.
Of all the stages in Sonic Generations, this stage is the only one that Sonic was never playable in the original game. Shadow the Hedgehog ventured through this stage instead.
Even though Sonic was never playable in Radical Highway in Sonic Adventure 2 story-wise (he was playable on the multiplayer racing mode), he has been there at least two times: During the intro of Sonic Adventure 2: Battle and Mario & Sonic at the Olympic Winter Games (Dream Snowboard Cross).
There's a huge blimp in this level that says "got ring?", which is a reference to "Got Milk?", like in the original.
It only appears in Act One though, as only Classic Sonic interacts with it.
The Soap blimp is not present though.
The blimp from the hub world says "got ring?" while the one from Act One says "got rings?".
In Act Two, there's some ads that say "Chao Soda" "Pizza Sonic 20: Anniversary!" and "Time Eater".
There's also ads in Act One, though they're pretty well hidden and the "Pizza!" one is not present at all.
The "Pizza Sonic 20: Anniversary!" ad is an updated version of the "Pizza Sonic 2" ad from the original City Escape.
This is one of the two city levels in the Nintendo 3DS version of Sonic Generations. The other being Casino Night.
Unlike City Escape, this level features Gold Beetles, and there are in fact more than one (as seen in a mission) but in this game, they disappear almost immediately after coming on-screen. Sonic needs to quickly homing attack them to reach a higher route.
The remix for Act 1 was made by Cash Cash while the remix for Act Two was made by Circuit Freq.
Despite it clearly indicates that you have to boost through the level, it's possible to complete the Special Trial mission for Modern Sonic without using the boost.
On a similar note, it's also possible to S rank the second act without using the boost. This is the only level where this is possible.
This is the only Nintendo 3DS level in Sonic Generations where Classic Sonic can go into the background and foreground.
Despite taking place in Radical Highway, the rival battle with Shadow doesn't reference the intro of Sonic Adventure 2: Battle, unlike it's console counterpart.
There are some signs saying "Route 00 Freedom ? Miles" around the level, just like in the original.
Radical Highway is the only stage on the Nintendo 3DS version to have a rival battle with a rival who went through the stage originally.