I really like the architecture you have going, but I think the lighting is not doing anything to complement it- it looks like its underwater. I’d say put multiple light sources and colours to bring out and show the depth of the tunnel.
I know I am late to the punch, but after seeing Cwook’s paintover I just had to try my hand at it.
I went with a desaturated blue light (Florescent) for the curved part of the hall way to try to get a “Mysterious” or “Dread” feeling from it since you can’t see where it goes. The light source would be over the door. The pipes help pull the two rooms together; I added a reflective property to the pipes to try to mimic what phong would look like. The reflective glow off the pipes would show the edge of the curved tunnel and draw the eye to the unlit end of it.
The warm orange/yellowish light from the off screen light would help keep the two rooms from looking like the same as well make it feel like this is the “Safe spot”. I threw in the electrical meter box on the wall to cut the light and make a shadow on the wall to produce more visual noise and contrast. The shadow would also help create a common ground between the two rooms.
I would also agree with Furioso; Exposed rebar and cables would definitely add a lot. I’d set up a env_shake on a timer to shake the cables and keep the environment somewhat lively.
Can’t wait to see what you do.