Piece
A piece in Tetris and similar games is a geometric shape consisting of a set of blocks that is moved as a unit. A block is the part of a piece that fills one unit of the playfield. In some games, all blocks that make up a piece are colored the same; in others, especially falling piece games other than Tetris and its clones, they are colored differently.
Polyominoes
A polyomino is a piece made of two or more square blocks, where all blocks are connected through full coincident edges (as if squares on graph paper).
- A free polyomino is one that may be translated (moved about), rotated, or reflected. These are used in Pokémon Tetris.
- A one-sided polyomino is one that may be translated or rotated. These are the ones used in Tetris.
- A fixed polyomino can only be translated.
Polyominoes come in several sizes:
- 1 block makes a monomino: seen in Super Tetris 3 (Magicaliss mode)
- 2 blocks make a domino: featured in Dr. Mario and Puyo Pop; seen in Tetris Blast, Super Tetris 3 (Magicaliss mode).
- 3 blocks make a tromino (or trimino): featured in Columns (fixed I only) and Pac-Attack (L only); seen in Tetris Blast (I, L) and Puyo Pop Fever (L).
- 4 blocks make a tetromino (or tetramino or tetrimino): featured in Tetris and its clones. Lumines uses only O tetrominoes.
- 5 blocks make a pentomino: featured in Daedalian Opus; seen in Tetris 2 + Bombliss, Tetris 64, Puyo Puyo Tetris etc.
Polyominoes are often named by a Latin letter that resembles the shape of the polyomino. For instance, an "I" has all its blocks in a straight line, and a "T" consists of an "I" tromino with one or more blocks in a straight line connected to one side of the center of the "I".
Psueudo-polyominoes
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| Pseudo-tetrominoes in Tetris 2 |
A pseudo-polyomino, also known as a hinged polyomino, polyking or polyplet[1] is similar to a polyomino but also allows connections at a point. In games that use pseudo-polyominoes, a piece may break apart at the diagonal connections when it lands, and the fragments may or may not be controllable afterward.
- 3 blocks: Pseudo-tromino (featured in EGAint).
- 4 blocks: Psuedo-tetromino (featured in Tetris 2).
Quasi-polyomino
A quasi-polyomino is any set of blocks regardless of whether they are connected or not. These are featured in Kowaris.
Other polyforms
Hextris and Bikaka are variants of Tetris that use 4-cell polyhexes, or pieces created from regular hexagons.[2] Bubble Bath Babes uses polyhexes that may be reflected around the X or Y axis but not rotated.