Warning: death and some gore I think

I was a monster/ghost hunter, a young guy (short hair, short jacket, tight pants, t-shirt) I had a water gun/bubble gun as a weapon, it had the possibility to mix the saint water with monsterbane herbs. I was a newbie, there was a young girl more experienced than me (black hair in two round buns, gothic lolita dress with black/blue silk) she had a weapon too, melee, but I'm not sure what she had.

Ok story

Big robots attacked earth, thing that didn't happen in years because of a peace pact we made. They came with some feral dog-creatures and attacked earth alongside them.

The survivors hid in an enormous building, '90 theatre-like. I came in the place with an older man, my mentor, but we went our separate ways almost as soon as we entered the place. I wandered a bit and found myself in the hospital-assigned part of the thing (the actual theatre). Armed nuns were taking care of the wounded.

Then the monsters attacked. No one in that zone survived, besides me. The young girl in the black dress came and helped me kill the beasts. Whenever the saint water or the herbs touched a monster, their dirty-green fur turned bright aqua-blue and then died. A few went kamikaze and left behind a spiky crest of something that resembled their fur.

Then the location changed, we couldn't move and we just looked in horror as the entire facility changed in the monster's favor. There were no corners or things I could jump or hide behind that they couldn't reach.

At last, we killed every monster, but they made their fair share of victims.