I'd have to give it to Planet Puzzle League for DS. So addicting, and very portable. A great value.
1. Planet Puzzle League - DS
2. Picross DS - DS
3. Tetris DS - DS
Honorable Mention: Polarium Advance - GBA
Kind of funny how they are all playable on the DS...
Whats your favorite puzzle game?
Top 3 favorite games: Super Mario Galaxy, The Sims 2 (PC), The Legend of Zelda: The Wind Waker