AMAZING game with really fun and smooth gameplay, and also an epic scenery! :)
All the different monsters you can dodge, boosts you can get and so on really add lots of fun and replayability to the game. Definitely consider making a mobile version for this, it's going to be lit xD
One thing that I think can be done with this particular art style would be like adding different background colors and also some more different things to see in there. Would look even more awesome and probably make everything more fun for a longer period of time ;)
Some upgrades and skins you can add to your character would be a neat feature as well