Mario End Game... is a rather infamous Super Mario World hack that changes literally everything about the original game. With original levels, custom bosses, sprites, music, graphics, blocks, patches, level asm and overworld, the game isn't so much an 'edit' of Super Mario World as it is a new game built on the same engine.
Plotline wise, it's just 'Mario saves Princess Peach from Bowser'.
You can see the 'trailer' here:
http://www.youtube.com/watch?v=0hO1Vvjgzjs
Oh, and finally, this is noted to be extremely difficult game. Partly due to a lack of open testing on part of myself and a little too much going on in every level. Save states are highly recommended.
Super Mario World (U) [!].smc
CRC32: B19ED489
MD5: CDD3C8C37322978CA8669B34BC89C804
SHA-1: 6B47BB75D16514B6A476AA0C73A683A2A4C18765
SHA-256: 0838E531FE22C077528FEBE14CB3FF7C492F1F5FA8DE354192BDFF7137C27F5B