This is reallly good. I'm very impressed at the level of polish here. The game also does a great job sticking to the 8 bit style. The colors feel right, the gameplay feels really on point for the style emulated, and the actual game feels very solid technically. Honestly when you go that hard to get this sort of style right with making sure that even one of the mushrooms has that sort of black outline indicative of the NES limitations its absolutely amazing. Music is good, game is fun, and I enjoyed beating it.
Also the idea to do a metroidvania is so on point. And not only that but it was all done by one dev for their second jam, bloody amazing.