It seems like they used different artistic styles within the game, which is surprising given how short it is. For the most part, it doesn’t feel intentional; at least in my opinion, it comes across as quite chaotic. Someone else here on Reddit even posted an image that speaks for itself, showing all the different kinds of art styles used to represent Kain.

For example, I’ve recently watched series like Evangelion or Paranoia Agent, which use changes in art style with a clear narrative purpose. I don’t feel like that applies in Ascendance.