I've an idea on a new way to do some collab pieces.

Basically, you start off with a canvas size and theme.

First person has two colours (background and foreground colours, of their choosing) to draw a concept base
Second person adds a further 6 colours of their choosing (to total to refine the piece
Third person adds up to a further 8 colours (total of 16) to again refine the piece
Then optionally any other steps allowing up to double the colour count of the previous step

When refining, artefacts can be added and/or removed, so long as the original concept remains the same. For example, say it was somebody shooting a gun, a muzzle flash could be added on a later step as the concept isn't changed, but the picture gets more detailed.

Given some of the concepts behind pixel art (low colour count), a single picture would probably be unlikely to have more than 4 steps. At the same time, you could make it hierarchical in the sense that if 5 people did the first step, the second "wave" could start from any of those 5. The third "wave" could work from any second wave pieces, etc.

Good idea? Silly idea? Anybody want to give it a try?