Basic structure test for a pixel-art background. I could use some c&c for prespectives, "feel" of the room and whatever. As soon as I'm happy with the result I'll add the details (doors, debris, light sources etc).
(http://www.2dadventure.com/ags/room_wooden2_copy.jpg)
the floor looks somewhat strange...are you trying to make it look like the walls?
The brick pattern doesn't look quite right. It changes direction about six rows down and near the bottom it looks awkward... Also, I agree about the floor. The texture doesn't really fit with the scene.
I think this is a good start for a background. Even though it's empty (at the moment) it's pretty interesting to look at all by itself.
I know you said you'd add light sources later, but you must have had one in mind when you were shading. Based on the floor and ceiling it sort of looks like it's right above the camera but it's not really clear.
Also, the bricks seem a little bit wide to me. Their lengths are four or five times their heights when they should be more like two or three, I think.
I think the ground texture would work (if you're going for cement) if you lowered the contrast some and did some tweaking, but I'm not entirely sure without trying it.