Because it was getting too large, the repository has been split in two:
There is an artwork or fanart images around the game area, to maximize it, and just cover the black border around with an image. Sometimes it's inspired from the artwork on the real cabinet, sometimes it's completely custom-made.
It makes your TV look like you're in front of an arcade cabinet. They have screen glare and scratches included in the overlay, and are configured to run with a scanline + curvature shader.
You can still find the old files in the backup folder.