Good hacks that are almost unrecognizable?

[benjaminshinobi]

I know I have seen some for Super Mario World, but wondering if anyone has any recommendations/knowledge about hacks of games that don't look like the original game: ie a Metroid Hack without Samus as the protagonist and made to look like an office building (as an example)

[Chpexo]

.

[PresidentLeever]

Duke Nukem using Alex Kidd's engine:
http://www.smspower.org/forums/15509-DukeNukemAKiMWHack