1) By being picked, it is implied that one should feel free to feel free. Do whatever you want. Wether that be playing an instrument or several to the pre-existing track(s), or editing, deleting, applying effects where and whenever you want, altering the pitch, tempo, tonality, re-purposing any and all of the materials included in the piece, adding music after/before/at any point of the pre-existing composition.
2) The number of ‘voices’/instruments playing at the same time shouldn’t exceed 4, unless absolutely necessary. It can always be less than four.
3) Please don’t remove single tracks in their entirety unless you absolutely must. In that case, do it. With a little explanation maybe (i.e. “I didn’t like it”).
4) Don’t use words.
5) There is a 3-week time-frame for every participant. Although such an album will most likely be underway for years, it is meant to be in constant motion. If inspiration doesn’t hit you within 3 weeks after confirming participance, please send a quick message that either you need more time or that you won’t do it after all.