Synthesia - A fun way to learn how to play the piano.
Piano From Above - Piano From Above is a program that turns learning the piano into a videogame.
Linthesia - Linthesia is a game. A game of playing music! You only need a MIDI file
Playground Sessions - Online piano learning game.
Midiano.com - Midiano is an interactive Piano-learning app that runs on any device with a modern browser.
Pianu - Learn to play the piano in your browser.