Puyo Puyo games are simple puzzle games that require the player to rotate falling pairs of objects to build combos of four or more of the same color. If the objects aren’t matched, they stack up and if they reach the top, the game is over. As the levels progress, players must rotate the pairs more quickly in order to survive, as the speed at which the pairs drop increases.
One commercially successful example of a Puyo Puyo game that I played as a child is Sega’s Dr. Robotnik’s Mean Bean Machine. The final level is depicted below, so you can get an idea of the gameplay.