Experimenting with Kajar's tileset, if it's shifted to 4B from 46, it gets a very dark feel. The only thing out of place are the stairs colours which are a vibrant teal...
I'll keep looking.
*Edit*
Ooooooh. Shifting it to 51 makes it an almost complete monochrome set, which is very nice. There only seems to be a few rogue tiles (IE: plants, healing square) that look weird.
2E shifts it to an interesting gold/black combination as well.
22 shifts it to a combination of dark walls, tables, and bookcases. However, the floors are a bright yellowish-orange.
1A also looks similar to 46. They both have a Black Omen-type feel.