Yea I think it would help to either go over the top by adding more to make your trolling intensions obvious, or continue the more gradual increase of difficulty that has already been happening from the start of the game by giving us a couple more screens that are harder but not so difficult all of a sudden in between. I would personally encourage the second option because, as you said, it doesn't fit the serious tone of the game that you have built so far, and that works very well. (I don't know Unfair Mario, but will check that out. sounds interesting)