Thanks for the feedback! Yeah the UI definitely needs an overhaul! I like the idea of staying in the arena, I could pretty easily just remove the background for now and then at least it wouldn't be such a jarring transition to a new scene.
Also 100% agree about not being able to know when you are hit, I was working on having the sprites flash white on hit but ran into an issue with the trigger correctly playing the animation and I ran out of time. I didn't think of it until after though but I think a little mini hp bar that would appear right above the Apples head when you take damage would help with that a lot as well.
Great feedback though, I appreciate it :)