I thought that this game has some redeeming values, but there's a lot that could be done much better. For one I found the controls to be really stiff, you do not want the player in a platform game to immediately get up to to speed (especially in a sonic styled one). Speaking of control, the controls are kind of awkward. Maybe change the dash button to double clicking instead of the shift button. Thirdly, the level design is all over the place and is almost always frustrating and punishing. The level doesn't feel like it was made with character in mind with there being way to many precision jumps, the difficulty is all over the place and there is a lack of telegraphing (my rule for difficulty is if you can't beat the level five times with out taking a hit, then its probably not going to possible for the player to do so), the materializing and dematerializing objects while cool looking are annoying to platform on, there are random floating rectangles that look like the can be jumped on but can't. I'd recommend drawing out a rough layout of your game on paper first and explain the inclusion of each of the sections. Lastly, the assets really don't mesh together well. I hope you'll make feedback into consideration, thank you.