Heyz... Some tips here
I'd do some changes..
Colors are very well chosen, but I'd try some "happy" colors instead.
I can notice those colors you chose make the game a little boring. and also makes the player want to go to sleep or something..
... When you JUMP, it kinda slows down... I'd check that out on the programming.
And.. well.. Sound could go with colors... Maybe a more action-like song. Or even a couple different themes too..
most important, the overall was pretty good... I kinda liked it besides those things... and I know it's a big thing to change.. but you can have this coment as a little help for the next game you make :D