In the City Escape gameplay I saw a couple of areas where you could freely walk around and 'explore' not that there will be anything to find mind you, but then again there wasn’t anything to find in SA1 or 2 either...
But there is plenty of exploring to be had in Sonic Generations, in fact I see far more genuine exploring in this game than what ever you could find in Sonic Adventure 2 and Sonic 06. When you get into the levels of those games the level is very, very linear.
In Sonic Generations I see multiple paths at every turn, multiple paths that often take skill to get too and will probably actually has something worth finding at the end... That to me is far more interesting.
Take the example Cube provided of Sonic 06 and then compare it to the complete run through of Modern Sonic on the new City Escape trailer, you will see more branching pathways in the first section than the entire level of Sonic 06.
City Escape:
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Not to mention everything about Sonic 06 looks so unfinished and terrible, the animations are disgusting, the way the camera moves so jerky and at times almost loses Sonic... the competely unsonic-like gameplay half way through with that Silver douchebag.
The loading times are painfully slow, not to mention the sheer amount of times it loads through one level... wtf?
The way you have to clear rooms of enemies before you can progress, so un-Sonic. What is with that infinate leg slide thing he can do? Where is any sense of self built speed or momentum? The enemies that take more than one hit to kill... WTF? lol at the way he flys upside down in the walls of water bit. It's like this game was rushed out in the pre-alpha.
It really is the lowest point of the entire series. It just straight up sucks.