[swyx]

(i mean yes i agree but) so ... why do i feel like ive never seen anyone do this before?

[udit99]

If you have a guitar handy, you can try out the live mode on https://www.fretboardfly.com . It works and people use it: Using your acoustic guitar to play the fretboard learning game via the mic.

[criddell]

I believe this is how Yousician works.