Have you thought of making an original game? I don't know - if it's just the personal challenge to see if you can do it, great. You've done three before so you've done this one too. But with the roms being able to be downloaded and hundreds of versions that are free to play (authentic or modified) already what other point is there to doing it again with another game?
Good point "destruk", I can say that I have plans to implement an original game, but the reason I'm doing specifically these games is way more personal than it seems, they are very important to me, I would not be a developer, and would not have achieved professionally what I have achieved, if I had not played these games and wondered if I could do something like that myself. Back then, after I started programming, unfortunately I never got really involved in game development. Then 35 years after writing my first line of Basic, I decided to recreate Prince of Persia, and this became a really emotional journey for me, what I could not predict was how exciting for me it became to know from inside out those games that were amazingly mysterious and fun for my teen self!
When I'm developing these, I picture myself like those guys that carefully assemble a boat inside a bottle, just putting piece by piece together.
I was planning to finish by Donkey Kong, but then I remembered about this annoying music and beautiful scrolling parallax effect (Moon Patrol was the first to implement it), I just had to do it 🙂