I don't know much of anything about Sega Saturns, but if yours is the same model as this guy's, it looks like the battery should be easy to replace. Probably easier than replacing one on a PC.

The only games I'm aware of for the Saturn (or, at least, in which I ever had any interest) are the port of Symphony of the Night, which apparently has the extra levels and the "play as crazy OP Maria" stuff that isn't in any other version that I know of (though it apparently also has visual, sound, and performance problems, and apparently the new areas aren't too impressive), and Panzer Dragoon Saga, the RPG based on the otherwise on-rails shooter series (the only one of which I've ever played myself was Panzer Dragoon Orta for the original Xbox). Oh, and I guess Nights into Dreams, though that one eventually got released on other platforms. Looking at the list of games, I don't really see any other Saturn exclusives that would've interested me much, especially of the ones that were actually released outside of Japan (which does not include SotN). Maybe Shining Force III. Possibly that Working Designs Magic Knight Rayearth game, even though I still haven't read/seen the manga/anime of that yet.