What are some alternatives?
When comparing Piano Notes Fun and Melodics, you can also consider the following products
Yousician - An interactive guitar-learning app.
Flowkey - The easiest way to learn piano with your iPhone or iPad
Simply Piano - Fast and fun way to learn piano
Jameasy for Violin - Play rhythm game with a real violin. you can play with background music and real-time feedback
Synthesia - A fun way to learn how to play the piano.
Chordana Play - Learn and practice piano using a virtual keyboard or external Casio keyboards.