According to your launchers.xml file, for example for the blur game, thumbs and fanart images are located into those paths :
Those 2 images appear as blank into XBMC? When you go into your C:\XBMC Games\Thumbs\ of C:\XBMC Games\Fanart\ directory are you able to see those pictures or they are blank?
The code you see here is AFTER I've manually added the images. Before, it was just Blur.exe_fanart.jpg and Blur.exe_thumb.jpg (No "c:\..." behind it), and they weren't saved in the default thumbs/fanart folders.
EDIT: I've made a folder inside my "fanart" folder called "blur", and put images there (named "fanart1.jpg", "fanart2.jpg", "fanart3.jpg"). I've directed the launcher to get the extra fanart from that folder, but it doesn't seem to work.
I've enabled extra fanart for TV and movies, and I'm using Cirrus Extended.