On these round robin ATCs, I was the middle player - I received a background, added something, then sent it along to another person to finish. I sometimes think the middle player has the most control over the ATC, and kind of sets the theme. Except perhaps in cases where the background is very specific. Certainly on a card like this, where the background is really undirected, that's true.
On the other hand, with this set, it was the final player who really set the tone, so maybe my theory isn't worth anything!