This was a concentrated effort by the SMB hacking "all-stars" to create the most difficult Mario hack the world has ever seen. I would say they succeeded. It spans ten stages with three bonus stages, and requires the use of every single technique that has ever been featured in any SMB hack in particularly twisted ways. As far as I know, only Quark (one of its creators) and myself have ever cleared it, but feel free to prove me wrong...
Download(Patch to "Super Mario Bros. (JU) [!].nes")