I had thought about maybe doing this in Block Abuse 2, but how about a mushroom bouncing segment where you must duplicate blocks diagonally in order to bounce the mushroom, all while key flying, and there's a huge bottomless pit below.
If you decide to use it and I come out with it first, don't copy it exactly.
--------------------Legacy custom music
How am I so creative? I think taking walks might have something to do with it.
Every single level I will ever make in SMM2 will be easier than Ultra Necrozma.