Pretty sweet demo!! I really like the spritework and music as well as the overall visual style :3 The speed you can gain in air is crazy refreshing and it's actually pretty nice to control, moreso in open areas than tighter ones tho lol
Some things I think could be improved upon are the momentum and physics in certain areas, mostly in run/jump speeds and on steeper slopes.
Whenever I try to increase my speed from a full stop, the build-up to top base speed feels pretty awkward timing-wise, while the sprites tell otherwise. It might be because of how quickly the camera pans to the side you're running to. Also, I noticed that jumps seem to kill momentum a bit while building speed from a stop and peelouts don't seem to put you at full speed, but it could also just be my classic Sonic momentum brain XD
For the slopes, Sonic kinda just doesn't like being on them very much. A lot of the time, he flings off of them while moving fast instead of clinging to them, and trying to gain speed by moving down them from a full stop (especially the steeper ones in this demo) kinda just.. doesn't work LOL. Again, the sprites say he is going fast but he's going pretty slow, and it's especially apparent when comparing this to rolling down these slopes.
Also I encountered a bug that prevents you from jumping while climbing steep slopes and noticed that if you tap to move from a stop repeatedly you can make sonic dance lolol
I know this is just a demo so I'm not critiquing or anything, I just wanna give some helpful insight into some things I noticed! Stupid excited to see what comes from this demo, it's already rather fun to play :DDD ALSO HATSUNE MIKU HELLO PEAK??!
thank you for coming to my TED Talk B3