This game is a lot like Sonic Adventure 2, but the demo seemed really limited to really judge the entire game. SA2 started out with very linear levels and got better...maybe this is the same...we don't know.
Kulock said:
So, tackle the general question: what's broken, and how should it best be "fixed"?
Games like this, and Sonic Wii, are simply diversions and distractions from what Sonic was all about.
When Naka and the rest of Sonic Team created Sonic, they created a platformer (perhaps the first) that placed emphasis on an advanced working physics system.
From that starting point, they designed other objects to interact with, using this system. This included not only gadgets to interact with to help you get through the level, but also parts of the levels such as ramps, loops, ceilings, and walls.
The most important trait Sonic has, and the one trait that defines him and his gameplay is the fact that he can roll. When he rolls, he can use gravity to his advantage and reach super speeds.
In the Sonic Adventure series...they did not completely abandon this system, but they hacked the physics in. So it wasn't a real working system, but they did make some effort to make it look so. It got worse in SA2, ie. you had the ability to roll down a vertical slope, turn around and roll up with no slowing down.
In Heroes it got worse again. The GBA games didn't have the same feeling as well (though Rush is a bit better IMO, and feels more like the Genny games, though I've only played through a couple of levels I need to play more).
Sonic Wii...*LOL* don't get me started on that...(it could be a fun game, but it's not Sonic...SEGA is just milking him when they decided to make that game).
SEGA got a license to use the HAVOC physics engine for this game...and I was HOPING they would use it on Sonic, or heck, in any aspect of the gameplay. Thus far it's only used on enemy physics when they fall apart after being destroyed. On falling objects such as boxes and rocks. And I think they are used on rings when they fall from Sonic. They are probably used on Shadow's vehicle as well.
But Sonic's physics are still hacked. He can't spin attack now (only does a spin dash), and the substitute for the spin attack is a kicking attack (WTF?), where he slides on his butt sticking his leg out to kick enemies.
Sonic was NEVER about homing attacks. Homing attacks aren't a necessity because Sonic can't be played in 3D...it was a necessity because Sonic Team sucks.

Seriously though, Sonic Team didn't realise that a fixed camera behind Sonic would be the most appropriate route, and that in 3D, Sonic should control a lot like a racer (not exactly like one, but a lot like one).
Turn Marble Madness into a full fledged platformer, and that would be more like how Sonic should be, than any of these newer games.
It has a fixed camera (that is easily adjustable, and could be used for turning the character), it features a full fledged working and fun physics system, and it shares many qualities with Sonic from a physics POV. It bounces off of surfaces, climbs up vertical walls, defies gravity, much like Sonic does.
There could be some out there thinking, "Why is he equating physics with fun?". To those I ask, don't you find Marble Madness fun? How about rolling into a ball in Metroid Prime?
Heh, here's a bold statement:
Metroid Prime...is perhaps closer to what Sonic should be, than any of these newer games.
Personally, I thought it was fun, and really, you could make an entire game like that and people would like it. Now, I'm not saying that Sonic should and will be in a ball at all times...that's only one part of it. If he has a complete working system while running, people will like it as well. He doesn't need to go any faster, but gamers will have more of a rush by controlling a real 3D Sonic game, than compared to a Sonic game that puts you on a rail and has you grinding at 3000 miles per hour. I can tell you that at some times, when attempting speed runs in Marble Madness, that I had a good rush from controlling this fast pinball through the level. Sonic should feel like that.
If there is any way I can become a lead developer of a Sonic game, I'd do it. If someone told me "you need to do A, B, and C, and then you will head a new Sonic title" I'd so do it, enough if it meant donating organs and limbs.

Ok, maybe not limbs. And not sexual organs.
-addendum-
Credit to Scullibundo and Dan for the diagrams!
-addendum 2-
Add Kameo to MMadness and MPrime...there were good and fun rolling physics there too.