What are some alternatives?
When comparing Piano Notes Fun and TuxGuitar, you can also consider the following products
Yousician - An interactive guitar-learning app.
Guitar Pro 7 - Create, play and share your tabs
Simply Piano - Fast and fun way to learn piano
MuseScore - 24 Sep 2012 . Design a homepage that captures attention and serves as a good starting point for navigating the website.
Melodics - Melodics is a desktop app that teaches you to play MIDI keyboards, pad controllers, and drums.
Sibelius - Sibelius is a virtual score creation tool which allows composers to easily create new piano scores, developed by Avid.