What are some alternatives?
When comparing Piano Notes Fun and Clone Hero, you can also consider the following products
Yousician - An interactive guitar-learning app.
StepMania - Rhythm game for Windows, Mac, and Linux.
Simply Piano - Fast and fun way to learn piano
Frets on Fire - Bonus content.
Melodics - Melodics is a desktop app that teaches you to play MIDI keyboards, pad controllers, and drums.
Osu - Osu is Music, Rhythm, Single and Multiplayer video game developed by Dean Herbert.