I was browsing through eBay (US) tonight, and came across a Bally Nitro Ground Shaker. Interesting in that, although it had a production run of about 8,000 machines, you rarely see one here either for sale on the forums or eBay Australia.
I have never played let alone seen the game. So for fun, I went on youtube, punched in NGS pinball to get a feel for the gameplay, and came across this link.
http://www.youtube.com/watch?v=oxm9x94eDnoAlthough the video is almost 10 minutes (with the last 6 minutes or so showing the gameplay), the first part of the video shows the story behind this owner's game - now that's a great find, and what a story!