The game is good, but I have a few things, that would make this game much better:
1. The interface (score, lives and time) look bland. Put them in a frame or something and if they cover too much of the screen, then make them transparent.
2. The lavels (1-9) look to similar and need more variety. Look at geometry dash as an inspiration. I haven't seen the rest of the levels.
3.
a) Make more effects (like add some SFX and visual effects when you die, touch the door, ect.).
b) Add some effects when you are close to the green wall (make the screen red, add intense music) and show the distance between you and the wall when the wall is not seen on the screen.
c) Make "themes" for the levels like lava theme, forest theme, ect. (Just make the colors of the levels different and change the music).
4. The music is so quiet, that I thought there was no music at all.
That's all I have to say. Good luck with the next games!