Pretty cool little game.
1- I liked the drawn characters, i feel it would have been better if the floor and background had a similar drawn look and wasn't minecraft :)
2-(if not playing on itch) the game doesn't scale correctly to the window size. works fine on itch though.
3-as far as i can tell there is no sound, if it does it doesn't playing for me
4- if would be nice to have more enemy variety(maybe something that pops out of the ground like the fish from the original sonic game)
5-The "How to play" button on the main menu doesn't work but this doesnt matter due to controls in the description
NOTE:I didn't check the jam time so i don't know how much time you had but its a pretty cool game :)