I honestly think the comment from Joggly Josh this is a valid assesment, after playing the demo, and noticing immediately that both the movment and jump mechanics are not even close to the original, making it feel extremely stiff to play. The Minimum jump height needs to be decreased, additionally you should reference pixel count as the Sonic 3 team did with Sonic 2 is my reccomendation. Mass is too high, acceleration and deceleration is not faithful as well.
The Nights Combo System doesn't even add score to your counter, and there is no use for it, as it stands right now it is wasted development time unless you like serotonin from flashing colors and numbers going up.
The method for Sprite rotation is jarring on render resolusion this small, with no menu in-game. There is no clamping or threshold to rotation so Sonic will jitter on any elevation higher or lower.
Music fades out into silence and does not loop.
Bugs are still present from the original as well.
The level design does not suit the hopping feature sonic has, either there are no spots to actually gain a speed advantage, no combo hopping to making platforming easier, or using it to access multiple routes. In fact it kills momentum completely with a hitbox snap so Sonic clings to it even if you don't want to use it.
No controls menu in game, or option for widescreen despite being a unique engine.
At this state it is not worth checking out, please wait for a update far later in it's development period for maximum enjoyment.
edit: auto correct inconsistencies