Acid Defender is a really cool concept game/Audio experiement. Its a synthesizer which a note for each column with the tone depending on where the white box is. Only there are little red “bullets” that fly into the screen and you have to move the notes to dodge them, because if one of the bullets hits a note you lose that beat.
In doing so you change the music, creating a continually changing piece of digital music, and a fun but stressful game.
I’ve only played this on a browser and the site says it only works in Chrome, but I think I game like this would come into it’s own on a tablet PC (iPad,Android whatever).
There is also a “Jam Mode” which allows you to just make music.