X-2 is heavy on the mini-games, and some are definitely better than others. Sphere Break is a pure math game. I don't remember much about the FFVIII card game because I was really bad at it, so I've blocked it all out. :P I did a lot better in FFIX in that respect.

I like some challenge in a game, too (that was my problem with KH2 -- way too easy), and never use walkthroughs the first time through. I don't think you lose the challenge of X-2 with a walkthrough, though; it'll just help you find some of the fussy things that can get you into trouble with it, like the aforementioned issue with losing almost all of the plot and sidequests in Chapter 3 if you go to Kilika too soon.