Good Romhacks and or Homebrew to put in?

I'm talking best of the best 'must have' be they little changes to make otherwise terrible games great (Simon's Quest Redacted comes to mind,) or complete overhauls only keeping the bare bones of the original game (there's this one final fantasy hack that is essentially one character set in a mystical feudal japan, forget the name of it.)

What are some rom hacks and or homebrew that NEED to be on the NES Mini now that we can add stuff?

Also... box art for these would be pretty nice where possible.