The concept is very interesting and fits the theme well. The art and sound design is gorgeous. There are however two very big flaws that for me took a lot of fun out of the game.
- It's not clear what's your goal. I started out the game without reading the description first and was very confused because I couldn't finish the level despite making it to the goal. The fact that you have to clear your ghosts before you can proceed should be stated clearly at the beginning of the game, otherwise the game looks like it's not working and you risk players quiting it at the first level.
- The stuff happening out of screen is super painful. Already in the second level, there is a fragment which requires you to go offscreen and performing a dash or double jump there is basically a game over, since you have to blindly search for the spot where you left your ghost, which is a huge pain. Also, because you didn't mention (in the game) that you can restart the level, it means that everyone who didn't read the description first is forced to restart the whole game.
In my opinion, this two issues should be fixed as they are a huge drawback to the overall presentation of the game. Otherwise, the game has a lot of potential and the mechanics along with the visuals and sound design could provide a very good experience.