I'm going to release the source code for it after I clean it up, so you'll be able to change it in whichever way you want to change it.
To "reskin" it, though, you'd probably end up just removing a lot of the layers in the frontend. Big Blue isn't really a flat skin. It's several layers of parallax scrolling and triangles. Right now, the sky background is 5 layers, the moon/clouds are 1 layer, the bushes are 1 layer, the crowd is 1 layer, the fighters are 1 layer, the Rampage monsters, R-Type ship, and buildings are one layer. A lot of the code in the frontend is just handling the game logic, so without any of that, it should be fairly simple.
I have considered putting out a separate frontend that's just the game list, image/video snapshot, background, and foreground layer with the ability to make the background scroll or not, but I haven't got around to it. Big Blue is just my personal dream for a frontend theme.
I've also seriously considered making a Galaga themed frontend for cocktail cabinets where two Galaga ships can fight each other, but I haven't come up with a great way to integrate the snapshots/video with the Galaga starfield in a way that doesn't look stupid.