I had some trouble with the next item on the Replacement Prize list, which PapaKrok requested for winning Character Contest 51. It was "spooky graveyard background", and this is what I came up with (now in Background-Standard):
Part of the problem is, if you get too complicated then the two-color limit really hits you hard. So I settled on doing something more abstract that hopefully will serve as a good backdrop for adding in other spooky bits to create the exact scene you want.
Update: Here's the Replacement Prize list: