Thanks for the (cough) low res image. 167k is still, quite huge.
The room, what stands out is its rectangularity of it all. It looks like HL1 with HL2 props thrown in for a bit of sprucing. This may be taboo, but my advice is to load some Unreal maps. I recently got to play AND finish Unreal II. I saw some outstanding maps contained within. I also noticed that HL2 should be able to handle almost any recreation, excluding the outdoor areas, nothing can compete with Unreal for shear scale out of doors. 
Be that as it may, ceilings and floors, walls and doors are hardly ever so flat. work on those.
and, work on your sense of "low res" please. 