You shouldn't judge Sonic Generations by the 3DS version of all things (
made by Dimps, the creator of the Sonic 4 games). It was okay, but it wasn't really a good game. I mean, even though I'm a fan of the homing attack, it was stupid for the 3DS version to give Classic Sonic the homing attack as a mandatory skill to use. If you don't like Super Classic Sonic being able to use the boost, then don't use it. This time, this is a valid argument. You truly, really, don't have to use the boost as Super Classic Sonic.
The PC/PS3/Xbox 360 version is far superior. And you're seriously complaining about them using previous level tropes?
That's the freakin' point. It's a game made to celebrate Sonic's past. What, did you expect brand new level tropes? In a game that's supposed to celebrate and recreate Sonic's past? At least Sonic Team used brand new level design. It's not like they copied and pasted the entire game. They took three years making the game!
Be happy that Sonic Team didn't go the Nintendo route and re-release the main Genesis Sonic titles with a music CD with a $50 price tag and call it a day.
Let's look at what stages were picked for Generations...
Green Hill Zone: Obvious choice to represent Sonic 1.
Chemical Plant Zone: Obvious choice to represent Sonic 2.
Sky Sanctuary Zone: Could have been Ice Cap Zone, but this stage works too as it represents one of the most epic parts in the story of Sonic 3.
Speed Highway: Very memorable, could've been another stage, but this works fine.
City Escape: Obvious choice to represent SA2.
Seaside Hill: Obvious choice to represent Heroes.
Crisis City: Obvious choice to represent 06. Kingdom Valley could've worked, but Crisis City was the best because of the Tornado That Carries Cars.
Rooftop Run: One of the most memorable stages in Unleashed. Obvious choice for representing Unleashed.
Planet Wisp: Obvious choice to represent Colors, as it's the home of the Wisps.
Yeah...I don't see much "generic-ness" here, honestly. I found each and every stage brilliantly designed and the graphics were amazing, especially on the PC where you can blast through the levels at a full 60 FPS (providing you don't have a bad PC) in 1080p (again, if you have a bad PC, too bad).
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Now, to go back on topic a little...
There's been a port of the daytime Unleashed stages for the PC version of Generations out for a while now:
http://www.moddb.com/mods/sonic-gene...eashed-project
It's amazing to blast through Unleashed stages in 60 FPS. It really makes a world of difference. I'd still take Generations over Unleashed, though. Generations has a lot more fun, 3D platforming. It also has better music, in my opinion. Unleashed is fun, but...Generations is better.
Also, calling Generations "Shiterations" is stupid. Don't ever use that term.