Quote@TheBitPriest - I like your thinking. Saying that, if we were going to have a mix of broad themes and specific challenges, why don't we let the topic setter be the one to decide each week whether or not (or how strictly) to have a ‘original art only' rule?
I think that could work. However, the reason I suggested alternating between broad themes and specific challenges was:
1. Participants could anticipate the scope of the contest ("June is here in a week... I can expect a broad theme. I'm in!")
2. The contest wouldn't be weighted too heavily in one direction or the other.