What are some alternatives?
Sampulator - Make (and record) beats on your keyboard
Piano From Above - Piano From Above is a program that turns learning the piano into a videogame.
BlokDust - Join blocks together to build sounds with this web-based music making app.
Synthesia - A fun way to learn how to play the piano.
Mubert - Electronic music generated in real-time just for you
Simply Piano - Fast and fun way to learn piano