The game is a really great example of minimalism done right, something that's taking me a long time to learn.
I've become really interested in technical art also, so there's a lot in here I'd love to pick your brain about. First thing I noticed were the smooth gradients and some kind of noise / film grain, is that for stylized debanding? I recently learned how to use interleaved gradient noise and blue noise for debanding.
Read your comment about the sharp shapes. The silhouettes and highlights are very crisp and readable. I've been learning vector art to help me compose readable silhouettes out of simple shapes, and then some stylized lighting would be really cool to learn next. Curious what your process was here.
Anyway, I got through the first wave without missing any parries! Felt so cool. I couldn't keep up that performance and failed on the next wave, but I'll definitely play again if just to marvel at the art.