I'm not as familiar with CGC cases, but are they like the top Rayman 2 case here on coverproject, the one closest to the retail box?
I'm just asking about dimensions of course.
CGC stands for Custom Game Case that our member Shadowfox makes.
The other case style is UGC (Universal Game Case) which is older thus currently more used.
CGC is bit superior due to it always been designed for spesific cart style where as UGC is fit all (not always that well).
CGC also fits N64 and SNES manuals perfectly.
Size is very similar and edit between the two cases is easy (spine width only if I'm not mistaken).
UGC is 3366x2100
CGC is 3431x2100
And no I'm not paid to advertise CGC.

I did buy the Virtual Boy case set and cases themselves are perfect.
As for other cases I personally only have 1 sample gotten from him as currently I don't have space to store games in cases, but will in future buy these cases.
As for Rayman 2 the style is one of the normally used styles called Horizontal or retail.
This is easiest to explain with Shadowgate 64 cover:
http://www.thecoverproject.net/view.php?game_id=854Top cover is Horizontal or retail in US style (red)
Middle is Vertical or custom in US style (red)
Bottom is Vertical or custom in PAL style (black)
There are also Horizontal or retail in PAL style (black) and both versions in Purple for Japanese (rarely used, but Super Mario 64 has both, altough I'm not sure are they pure examples or are the backs modified).
There are of course other unofficial styles used.