Thank you for playing Sorcerer6, and I apologize my answer is late.
WERERAT is still living but he is HIDING. He is at a corner of LARGEST block on B1F, at Southwest quarter. Search every corner, and you can find a SIGN. After you see that, WERERAT will be appeared soon.
> I cannot find NPC The Wererat! I think possible I killed accidentally? I have completely cleared floors 1-3, most of 4 (except top-left), all 5, and been to 6. A hint on finding him, please, so I know if I need to reset and start over?