Thanks for such a detailed review! I definitely used reaction time to up the challenge quite a bit. Not only do you slowly approach the edge of the screen in each stage, but, like you said, it gets reduced significantly in stage 4. It was definitely intended to up the difficulty with time.
I used visuals to keep things challenging and simulate Azul's own difficulty seeing and dodging attacks. This is especially the case with the blizzard in stage 3. However, I definitely see how the arrow's size could get frustrating, and I'll keep that in mind going forward! It's no fun if you cannot see the threats at all!
All in all, I'm quite glad you enjoyed the little story I told and the way I told it. Thank you for playing, and for the useful feedback!