This is a hack that has you going through a min. of 100 rooms filled with enemies with an occasional power-up. At the end is a fake Bowser and a door leading to the final boss. All that in four levels! WOW!
Super Mario World (U) [!].smc - GOODSNES 2.04
CRC32: B19ED489
MD5: CDD3C8C37322978CA8669B34BC89C804
SHA-1: 6B47BB75D16514B6A476AA0C73A683A2A4C18765
SHA-256: 0838E531FE22C077528FEBE14CB3FF7C492F1F5FA8DE354192BDFF7137C27F5B