Xeep is a very interesting and strange little musical arranger that is good fun but I'm not sure if it is anything else. Which half infuriates me.
But good fun can be enough. The software works by creating a different musical note depending on where you point your stylus on the screen. It can produce octaves and thirds and the more notes you play the more colourful the screen becomes.
So you get full sound and vision aesthetics.
If you are good enough you might be able to compose small pieces of music but on the whole I found it was more like a little musical toy that's nice to experiment with and make colourful patterns.
Once you've created a 'musical score' you can adjust the tempo of the playing to find which speed best suits your piece. Yes it's strange but it's also quite fun.