Only new game I've played that seems worth it so far is Ninja Gaiden - Dragon Sword, but the difficulty level is ridiculously easy for a Ninja Gaiden game.
I heard FF crystal chronicles is on the DS now, and there putting Myst on the DS as well, I'm getting that for sure.
i didn't like ninja gaiden that much, but i found a new gem: The World Ends With You
an action RPG developed by square enix, i feel that it does many things right. the animation is fluid, the fighting system is fun, the soundtrack is unique, the main character's a jerk but he gets better.
not to mention you could accumulate experience even if your DS is turned off. and you could adjust how much level/HP you have - thus casuals can leave their HP on high, and more hard core players can set it to the minimum (and increase their chances of picking up more/better items).
my only complaint is that there isn't a multiplayer battle mode. that would've been awesome.
Yu Gi Oh is a good game. You dont have like the anime, btw, to like the game.