Interesting idea, but didn't work so well for me because all the notes was hard to hear - ambient sound was a lot louder than the notes and I only heard that they are there after reading comments and looking at the example of the first level. Also I am not sure having invisible note tiles is a good idea... its difficult to find them sometimes (level 2 was the worst with them positioning quite randomly!) and it harder yet to remember all of the positions and notes relative to eachother (with notes being hard to hear and imposible to hear again after failed step). Starting from second level it became just "try all and see if it sticks" for me :(
I did defeat the melody lich though. It just... could be so much better if I could actually hear the notes and repeat them somehow after fail step too.