One or two games also used the slot for ROM. I've King of Fighters '95 that had a ROM cart and CD. The ROM cart was only for that game. Later Capcom/SNK introduced RAM cart that could be used with different games and just served as extra RAM. I've that as well with pretty much all the Capcom fighters.
I bought lot of imports for my Saturn. Still have all the stuff including the Virtua On TwinSticks, Bomberman multitap, ROM and RAM games, and probably about 100 games including Radiant Silvergun, Panzer Saga, Shining Force series, Dragon Force, etc. One of my favorite consoles as I was a serious Virtua Fighter nut back then.