So, how many people here enjoy this kind of thing?
I've occasionally had some fun playing Cat Mario/
Syobon Action (I'm sure most people here will have come across it at some point). It's not actually very hard to beat; in fact, it's much easier to finish than normal Mario on account of the small number of levels and the infinite lives. It's also very satisfying, since you can see how much progress you are making.
I've also dabbled with Unfair Platformer, but I didn't really enjoy it as much (Western sh*t with annoying "Spring Yard Zone" music
)