From Halopedia, the Halo wiki
Well, I was thinking more along the lines of what Overwiki did with those extra images.
Well, the concept of having subpages for images has been floating around my head for a while. XP
That's a good idea, actually. However, we're not ready to use such concept because we all know that Halo fans love uploading their own "cool/awesome/epic" screenshots that has little or no relevance to the article. It will end up becoming "my pic is cool enough to be in the main article" issue. :P
What background image???? Can you add the Image URL? *confused*
Ah, that "bold" as in bold text. I was thinking of something else... XD
As for the ONI foreground (I think, that's what you meant by grey background), I think it's suitable for the wiki and doesn't attract much attention; it is simply a nice decor that improves the wiki's appearance. If the foreground is improved (by means of making it saturated and more eye-appealing), then the text in the articles wouldn't be readable. In other words, it's a conflict of display between the content and the foreground.
I would really suggest talking to Template:Name or Template:Name if you have any suggestions to improve the overall theme. The only thing I can do is improving the Main Page design/layout...
Regarding the overly-bold rounded boxes; rounded boxes is more eye-pleasing than hard-edge boxes. As for the overly-bold, I think that's the fault of the Century Gothic. I've added alternate fonts for those not having Century Gothic in their computers.
As for the grey background, care to elaborate?
I suggest talking to User:Porplemontage about this. :)