Under rating threshold (hideshow)
Hmm...doesn't require very much skill, and I actually liked the Red Remover one better, though I still will rate it 4/5, great.
Under rating threshold (hideshow)
I think the maximum amount of under par levels is 12, I have got 1,2,4,6,8,10,14,15,16,17,19 and 20 all done under-par. I think that with a bit of luck 9 is also possible under par too.