Interesting concept, I think I've seen a mod like this some time before but that was many years ago and it was not this elaborate

It doesn't really give me the nostalgic Mario feeling. The colors are very very dark and I think you should definitely change them. Instant Eyedropper is an incredibly simple and small program that can help you identify RGB and Hex colors, very useful for all type or artistry.

Doesn't look like a ton of fun to play, it feels very empty. Hope to see some new cool mechanics and perhaps even smaller dimensions. Keep it up