Puyo Puyo, originally invented by Compile Corporation, is also known as Dr. Robotnik's Mean Bean Machine on Sega Genesis, Kirby's Avalanche on Super NES, Candy Crisis on Macintosh computers, Puyo Pop on Game Boy Advance, and freepuzzlearena Vitamins 2 on Linux, DOS, and Wintendo.
The game is played on two grids 6 squares wide by 12 squares high, one for each player. (There is often a one-player practice mode.)
Pairs of tiles/blobs (depending on the chosen theme) fall from the top of the playfield.
The player can rotate them or move them sideways as in Tetris or Dr. Mario.
There are three to five colors of tiles depending on difficulty; four or more adjacent tiles of the same color will explode into points, and the tiles above them will fall into place; tail recursion of this process produces large chain reactions for even more points.
A large number of points will also dump boulders on the other player's playfield; get rid of boulders by making a normal explosion next to them.