Nice architecture, decently detailed. Love all the ruined bits. I noticed a graphical bug under one of the staircases (see demo).
Skill 2 combat is a bit on the tough side (died 4 or 5 times) but not too unfair. I liked how you used the zombies as unkillable turrets until the player gets a GL and/or quad.
Secrets were nice - only got the YA one after it could be of any use, though, but that's totally my fault: I should've known that these tiny ledges near the stained glass windows were there for a reason...
Here's my blind skill 2 demos
, 100% kills, 100% secrets.