Very solid player movement!
The stops between transitions and yoyo swings pulling you along made it feel quite authentically NES, as well as giving the player time to prepare for the next input, making going through the level very intuitive and fluid.
Love the yoyo mechanic, traversal is a lot of fun once you master it, and still fun while you're getting used to it.
Took me a bit to get used to the nuances of it, like how the up swing is a bit forward and up so you'll miss trying to swing at stuff from directly below.
Love the additional challenges thrown into the main area, traversing from one side of the street to the other from the top was easily my favourite! (the timing for that last bit is tricky, much earlier than I expected)
The boss was fun, if a bit on the easy side, but it matched the overall challenge of the rest of the game, so it makes sense. I do wish it maybe went higher once it got to half health or something so you couldn't just beat on it from below the whole time (aside from dodging the one ground covering attack) (ps. I did spend the game wondering if it was going to make that reference, and I was not disappointed, haha)
Only nitpick I have is that the game could have a bit of a grace period after you finish a level before letting you reenter, or just close off the doors that no longer have something new to collect. I ended up redoing a level I'd just finished because I'm a bit fiddly with my controls and tried to upswing the yoyo before moving away ^^;;
8 Bones collected! Not sure if I missed any, could maybe do with a message at the end that lets you know how many there were in total.