Picross DS was a game that I played continuously for three years - something I can very rarely say for any other game. Hell, even if the game ended up being a straight port, I would buy it day one. There are thousands of puzzles, and all of the user-created puzzles will keep the game fresh for a long time.
Nintendo just needs to release Jam with the Band E for eShop and we'll be set.
Playing: Shin Megami Tensei: Strange Journey, The Legend of Zelda: Link's Awakening, Stacking, The Legend of Zelda: Ocarina of Time 3D, inFamous