As you can see...My Aura playthrough months ago on NIGHTMARE difficulty has yielded the near-perfect score of 254, just short by 18 points. NO corruption whatsoever, fully resisted Alicia's influence.
And I won. Against all odds, on day 100 on Nightmare difficulty.
So yes, doing a 100% pure run is not only possible, it is also rewarding in the end because it makes you feel like this is the very same Aura who beat Richard the first time in the prologue, only MORE seasoned, experienced and now truly his equal even without the Divine Gift.
It is very rewarding seeing Richard break down and get furious and it's even more rewarding to see him get what he deserves.
Once more like a broken record:
100% PURE. NIGHTMARE RUN. UNIMAGINABLE PAIN!