Just because it's a fangame you don't necessarily have to make a exact copy of the original gameplaywise. For example, wouldn't you consider Dream vs Dream a fangame?
I'm not saying you have to be that radical, but if you ever want me to start playing fangames again more than once a year, you'll need more than a wanderfest to get me interested, no matter how pretty the wanderfest is.
YN was a wanderfest. And that was fine, because it was the first of it's kind. It worked because it was new and unique. But it's a type of game that does not stand being played over and over. You need to put something in the wanderfest to make it more interesting.
You can still HAVE a wanderfest, but you can also have gameplay, and you SHOULD. If I ever make another YN fangame I will definitely have some kind of gameplay.
You can still have all the things that made YN unique, like weird locations, mysterious creatures, exploration, dreamlike landscapes and the general mood of the game. Fangame is a broad enough term that you don't need to make a copy of the original to be able to call it a fangame.