I'm wondering if you can add an advanced variant of this, where the player doesn't have to go through the usual progression of notes building up one at a time. I played another app like this, and I got bored quickly because it would keep starting with one note.
It would be nice to have a more challenging mode which presents a melody of 4 to 5 notes at a time. Also, it doesn't have to repeat in the next round -- instead; a new random melody is played. That would test not just one's memory, but would provide interval training as well.