Okay so after playing this for a bit, I do think that this is a game worthy of being on the portal. Physics wise, this is actually pretty solid and I like the fact that you're going for NES level difficulty. Yes, there are difficult sections but for the most part, they aren't totally unfair.
The one part I'm struggling to get past is the section inside the building were I have to wall jump on a moving platform to get to a heart. While that is an interesting challenge that could reward the player I feel like something like that should be optional for those who are willing to take on that challenge as opposed to being forced to do it to move on. Otherwise it kind of feels unfair for those who haven't fully mastered the wall jumping mechanic at that point.
BUT OVERALL, I like the direction this game is going. The pixel art is a plus, but it would be nice if it had a true 8-bit aesthetic given the kind of graphics you're working with.