I’m no Stahlberg, but I’ll give it a shot. =)
As most people pointed out, the red glow on the floor is not enough to illuminate the ground, so you should probably tone it down alot and make it more subtle.
You have however a huge glass behind the throne that for some reason isn’t letting any light through. That’s your best shot to get rid of the flag effect Steve mentioned by adding colour of the the outside environment (whether it’s green or blue doesn’t matter, I used purple) in the interior.
I had a big problem to sort out the windows in your sketch, but you should probably try to get them well defined so you know exactly where they’re coming from. Don’t go overboard on the volumetric light, instead use the outside light to show your nicely detailed ceiling.
Last and not least, you had the throne as the heart of your image on an earlier version. I don’t know why you got rid of it, as it clearly defined itself as the point of interest of this image. I’d say to stick with it, it has this altar quality to it, evoking mystery.
You’ll notice I made the back glass larger, but that was unintentional, I missed the right outlines for it. :shrug:
Here’s the rough overpaint:
