I'll vouch for custom robo arena; that was an awesome game.

Lunar knightsand N+ too

But if you get into importing games, no. 1 on your listshould be Fire Emblem: Shin Ankokuryuu to Hikari (aka FE: DS). It's only in Japanese but its not too hard to understand, there are places on the net that'll tell you what's what. It's an AWESOME rpg/ turn-based strategy game, and if you can beat it on hard mode 5 in a reasonable amount of time then YOU ARE FREAKING GOD. uuuuubbbbbeeeeerrrr hard.

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