I definitely like what you're doing here, but I'd say you still have work left for you in two key areas.
The lighting is a bit basic. It works for the atmosphere you're trying to build and it gives off a classic beta vibe, but unfortunately it's beta in quality too. Work on the brightness -- some areas are a bit too dark, others need to be darker. Create a contrast with brightness alone so that the player constantly switches between them as he travels. It makes him weary and cautious. The color palette needs some refinement, as well as the positioning. In the first picture with the banners, each of them has a different color, which overloads the viewer's sensory input (a fancy way to say eyes). While such a theme works for a cyberpunk setting for example, it doesn't fit what you're going for.
Also, use clever saturation and desaturation of colors to better adapt the lighting -- desaturate your overall lighting and only saturate the highlights -- such as posters and so forth. If there's too much saturation going on, the viewer will be overstimulated and will grow tired. If there's no saturation and everything's grey and dull, they'll get bored. There's a fine balance between both.
As for the second point, the brushwork looks interesting, but it needs some detailing. It's rough and edgy. Smooth it out a little bit and introduce some props and models. It's too empty and it lacks a personality -- use graffiti and posters on walls to achieve that.
I can talk in specifics if I could take a look at your compiled work. This is just a general overview. I understand if you do not want to do such a thing.