About this game
How a key signature works
The sharps or flats at the start of each line are the key signature. They apply to every note with that letter, in every octave, until the music says otherwise. One sharp on the F line? Every F is F sharp.
Sharps always show up in the same order: F, C, G, D, A, E, B. Flats go the other way: B, E, A, D, G, C, F.
What the natural sign does
A natural sign cancels the sharp or flat for that note until the end of the bar. An F with a natural sign in G major is a plain F.
An extra sharp or flat in front of a note is the opposite: it changes a note the key signature left alone, again until the bar ends.