The Invisible Orchestra is an electronic music experiment. Using a collection of computer algorithms that rely--to an extent--on randomness, each week (or month?) we generate a collection of "riffs"--6 melodies and 4 drum tracks--for you to create original compositions with. Some riffs are more random than others. Some weeks' riffs will be more conventional and listenable. Some will be more...well...difficult.
You--the "composers"--will build compositions out of computer-generated "riffs". Riffs are simply midi-files, which include no information but which notes to play or drums to hit, how loud to play them, and for how long. Composers choose the voice and arrangement for these riffs. Sections might be looped, silenced, effect-laden, cut into pieces, etc.
The songs might be barebones, or they may include original (human-generated) riffs.
From week to week, we might tweak both the algorithms that generate these riffs, as well as the Rules of Composition (must composers use all available tracks? are human compositions okay? outside samples? vocals?)