From Hard Drop Tetris Wiki
Puyo Pop (called Puyo Puyo in Japan) is a non-tetromino falling block puzzle game franchise. It was originally conceived by Masamitsu Niitani, drawing heavily from Dr. Mario, and developed by Compile Corporation, which folded. Sega continues the series on major video game console and mobile platforms.
Dominoes, each side colored with one out of three to five colors, fall into a 6x12 block playfield. The player can move them sideways or downward, and/or rotate the "secondary" block about the highlighted "primary" block. Dominoes that land break up into individual blocks and then form groups of horizontally or vertically adjacent blocks of matching color. Four or more blocks in a group explode, and the blocks above them disconnect, fall, and reconnect.
Sticky Tetris, the primary game mode in The Next Tetris and one of the modes of Tetris Worlds, borrows this play mechanic of removing groups.