What's you're favorite puzzle game?
I gotta say the best puzle game I've ever played is Wario's Woods for NES. The Super Nintendo version was basically the same but with a couple slight differences I didn't like. But Wario's Woods is one of the most original and fun puzzle games I've ever played. Great multiplayer too. I was psyched to see it again on Animal Crossing.
As far as chalenge, I wonder if anyone has ever played Wetrix on N64. Now that was a challenging puzzle game. I managed to get an unbelievable score once. Wonder how long that game lasted? The multiplayer wasn't as good but still a very welcome addition.