Jesper Juul, an academic studying games and a self-styled "ludologist," is putting together a history of matching tile games, starting with Tetris and Chain Shot and spanning down and outward. Though he calls them the "most disrespected and despised game genre there is," he's worked out a very neat and eloquent classification system, and I bet there are many of us here who could add titles to Juul's list. He asks, "Am I missing a game that contributed to the history of matching tile games? Do you find the connections playsible?" Check out his diagram and see what you think.