# Difference between revisions of "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 one 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:

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".

## Pseudo-polyominoes

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.

## Quasi-polyomino

A quasi-polyomino is any set of blocks regardless of whether they are connected or not. These are featured in some fan games, such as 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.

## Polycubes

A polycube is a piece made of cubic blocks, where all blocks are connected through full coincident faces. These are featured in 3D variants such as Blockout and 3-D Tetris.