I really don’t know, since we want this to be open to as many people as possible I feel we’re limited to paint/colour challenges rather than something like paint a vehicle/monster or something so specific.
So my current thought is a limited palette like monochrome, doesn’t have to be greyscale, could be red-scale. Or primaries + black & white. Or the Zorn palette, here’s folder favourite Marco working with it:
Or down the technique path of NMM or OSL or something. Both things I’ve hardly used and would like to give a go or.
Or something l