Who here can read Japanese?

You want hard?

[video=youtube;r86NLwCYXfk]http://www.youtube.com/watch?v=r86NLwCYXfk[/video]

pimento Mario Stage 2
pimento Mario Stage 3
pimento Mario Stage 4
pimento Mario Stage 5
pimento Mario Stage 6
pimento Mario Stage 7
pimento Mario Stage 8
pimento Mario Stage 9
pimento Mario Stage 10
pimento Mario Stage 11
pimento Mario Stage 12
pimento Mario Stage 13

There's also an pimento Mario 2. Here's stage 1, and you can follow the links in the comments to watch the rest. Even if you don't want to play 'em, they're really entertaining and edited really well. The best part about it is that it's an actual guy is playing on them and discovering each of the pitfalls for the first time, rather than the guy who made it or worse yet a frame-perfect run. No doubt though, the player is incredibly skilled.

If you want to actually play them (god help you), I uploaded them here. You will want to find and activate an infinite life cheat. I think any regular 'ole Super Mario World one should do.

That's actually called Kaizo Mario World, I've played it and only gotten past the first 3 levels before giving up. o_-