Not much for theme since you actually can stop moving.
The special object sure is there and is a large part of what it is.
Unfortunately there is not much game there. I tried to fail and actually had to try twice since it is SO hard to fail this, just running your mouse from left to right will give you a lower score but you will most likely still finish it.
Maybe being a bit harsher when you stray from the line could be good. Having multiple lines you have to draw on the same painting, all in a different color and making it partly time based would be a good addition too. You start with a 1 million dollar painting and lose some amount each second plus some amount based on how far you are off the line. That way it becomes an optimization puzzle.
Still, for just 12 hours it's not bad so kudos !