About this game
What sharps and flats do
A sharp moves a note up one half step: the very next key to the right, black or white. A flat moves it down one half step, the very next key to the left.
Every black key has two names. The one between C and D is C sharp and also D flat. Which name you see depends on the key of the piece.
The tricky ones
Some sharps and flats land on white keys. E sharp is just F, and C flat is just B. This game skips those at first, so you can build the habit on the black keys.
An accidental also sticks around for the rest of the bar, on that line or space. Next bar, it resets.