Awesome game, especially the concept! I think there are two things holding it back:
The 1st level doesn't have any enemies which you can lure into your trail, which obscures the game mechanic a bit.
It feels a bit awkward how the trail doesn't immediately come back after respawning from taking damage. In my play experience this led to more inconvenience than help, as when my invincibility ran out I would immediately go back for some reason and hurt myself again. To be honest I'm not really sure why I did this, but for some reason I just kept doing it without meaning to. I think it would be better for the playable character to always generate the trail so that unusual behavior like mine is more swiftly discouraged.
Super creative and super fun entry. Love the art, love the music, love the concept and story - Well done!