I could be wrong but i assumed you could collect the "souls?" and unfortunately you cant.
The art style and visuals are absolutely amazing! The fog adds a lot of atmosphere and match the art style perfectly. It looks very high quality and very professional. the mechanic of wall jumping is something i like too.
I wish the collectables worked as i think that is also a nice touch.
If i was to change anything id try adding texture to the platforms as i hink that would look good.