You may be able to glean some info from the Official Site
I, too had to find out what all the hubbub with Yu-Gi-Oh was about that had all the kids in a craze. On the weekends, the card shop by me is literally swarming with waist-high kids screaming about YuGiOh! I ended up getting the World Championship Tournament for the GBA. Not much of a story, but it plays a good enough game.
I suppose you could compare it to Duel Masters which is a simplified version of Magic: the Gathering. There are a few tweaks to make it different, but it's pretty similar. Since you've played MtG before, after a couple games you should have no problem playing YuGiOh.
Play some games of that with the kids, then try to push them toward the real
card game, Magic