Yousician - Learn to play music at home, at your own pace
Melodics - Melodics is a desktop app that teaches you to play MIDI keyboards, pad controllers, and drums.
Synthesia - A fun way to learn how to play the piano.
Guitarix - Guitarix is a simple Linux Rock Guitar Amplifier for https://alternativeto.
La Touche Musicale - With La Touche Musicale, you can learn piano online easily with the songs you love. Discover a fun and effective learning method to progress very quickly.
TuxGuitar - A Multitrack tablature editor and player.