Children learn patterns before they learn names. That is why in this game every note has a consistent color: C is always the same color, so is D, and so on. The child first recognizes the note by its visual pattern and gradually anchors the name to its position on the staff — the natural path for someone still training both ear and eye.
A guide line connects the note on the staff to the matching key. That removes the guessing: the child always has a way to get it right, and the confidence of getting it right is what keeps the play — and the learning — going.
The colors and the guide line work like training wheels on a bicycle: as reading gets steady, they fade away and the child moves on to reading real notation, in the same game adults use to build speed.
For parents and teachers: it runs right in the browser on a tablet, phone or computer, nothing to install. A few minutes a day is enough — it is reading practice disguised as a game, ideal as music-lesson homework.