I eventually managed to beat each of the 4 levels, although definitely not with a single same credits (it took me around 3 hours ;) ).
My expectations for the game were high and the game was ever better than I expected. The game is pretty much a NES game, it looks great, it sounds great, it controls great. I love all the things you can do with the yo-yo, and I also love that you're not forced to to be able to beat the provided levels. The levels are excellent, I love the bonus rooms (especially the hidden one in the last part of the last level, as the hearts from this one are welcome) and the alternative path of the last level and the length of the levels and overall difficulty are perfect for the jam.
I thought the invincibility when you get hit could last slightly longer.
Thanks for sharing!