Some suggestions for you.
- If you want the player to jump in small platforms, you probably need to let the character be able to turn the direction instantly. In your case, the character would often fall out the platform due to the turn mechanic.
- Since you have a white/black background transition, it would be better to change the color of platforms too. It's pain to jump between white platforms with a white background.
- The music and sound effects are fine. But just don't fit the style of your game. You would probably need a pixel art character for this type of sounds. Otherwise, it's better to use a more modern one.
The idea and concept of your game is okay. There are just some improvements that can make your game even better.
It's also good to see that you made the volume slider and dialogue system.
Keep it up.