I thought the way you used the theme was cool and unique. I had a lot of fun playing and trying to get further through the stages, but the enemies really start swarming you after a couple. Messing with the Yoyo was fun, and the trails it left behind was a nice detail. Also, the scene transitions was a nice detail
I think the KUBBI music fits the game pretty well, and it’s been a while since I listened to their music, so it was cool hearing it. Also, having the songs be randomized in the menu was nice, and I kinda just sat in the menu and listened for a little.
The SFX was well done too, and I enjoyed how well put together it all was. It definitely immersed me in the game.
Your menu design is really good. I like how the Yoyo comes down to the buttons. It was cool how you stylized it, too. The font choice worked well, and I liked how the options got highlighted when you hover over one.
Something that I think you could improve is the pause and upgrade menus by adding SFX to them.
Overall, I think your game is a nice, short, well-polished experience. I’m going to go play some more of it now, those spiny enemies keep surrounding me on the later stages.