I have a collectors question about Planet Ring.

I've been looking for the game on eBay and I've noticed some copies with a blue spine (with the "Dreamcast" logo on it) and some (usually cheaper) with a generic clear over a plain white colored spine. Since most of these listings are European and don't really give too much information on the condition,but are the ones with the clear spines legitimate? Is it just that this game was issued in a plain-looking case by itself and then in the boxed set with microphone with the blue spine? I'm coming here because hopefully a fellow collector knows what to go for, as I can't find too much about this!

Thanks to anyone who can fill me in!