Synthesia

Synthesia is a video game for Windows and Mac OS X which allows users to play a MIDI keyboard or use a computer keyboard in time to a MIDI file by following on-screen directions, much in the style of Keyboard Mania or Guitar Hero. It was originally named Piano Hero due to the similarity of gameplay with Guitar Hero; however, Activision (the owners of the rights to Guitar Hero) sent a cease and desist to the program's creator, Nicholas Piegdon.

The program was originally Windows-only, but after a donation-drive in early 2007, the game was ported to Mac OS X.

Synthesia was originally an open source project, but seeing the potential commercial value of the program, Piegdon decided to stop releasing the source code (version 0.6.2), however leaving the most recent open-source release available for download. While the basic functionality is still currently free, a "Learning Pack" key can be purchased to unlock additional features, such as a sheet music display mode.

The game will work with any MIDI file and display it as falling bars and aims to be able to teach beginners how to play the piano.

Cease and desist letter
In a letter dated 26 March 2007, Activision requested that Piegdon "immediately cease any and all use of the "Piano Hero" name in connection with the distribution and promotion of [his] video game and agree not to use such in the future". Piegdon responded by hosting a contest for a new name for the project, resulting in the current name, Synthesia.