I can make some sheet music, if the game gets that big.
Rests: , - .(brackets are needed, for example (, - .).)
For the time, its the same as piano, so you can go search up some Youtube for that.
The game can't use long notes, so I'll request that. For the meantime, for long notes, there will be
A second: '
Half a second: - '
Tuning is going to be the same as piano, so I recommend knowing things about piano before using this.
For the normal notes made by the dev, just write the letters.
Also, minor notes should be A, S, D, F, G, H, J, K and L.
I can't be bothered to write more, since I haven't even played the game much. There are so many things to elaborate on, types of scales, how to use the rest of the keyboard, and all kinds of other things. You can also make more concepts and things in the comments. I want all of your feedback.