Tetrominoes start out centered, rounding to the left. I goes in columns 3–6 counting from the left, O in columns 4–5, and others in columns 4–6. Each tetromino starts with its topmost solid block in row 20.
Each tetromino is ordinarily spawned flat side up. There is no initial rotation and no wallkicks. Additionally, the ceiling prevents rotation.
Apart from I and O, all tetrominoes rotate such that the bottom of the tetromino is at the bottom of the piece's bounding box. S and Z rotate between two states so that the center column stays constant. O does not rotate; I rotates between two states as depicted in the illustration.
The differences between this and many other rotation systems are that the flat-side-down states of J, L, and T are pushed down by one space, that S and Z round in different directions, that I rounds differently from the other pieces, and that I requires more space under it to rotate to a vertical orientation.
It originally used no wall kicks. Arika took inspiration of this rotation system, adding mild wall kicks and initial rotation to their own rotation system. This modified rotation system is called the TGM Rotation or Arika Rotation System (ARS). In addition to the TGM series, most arcade games developed in Japan before the guideline followed the Sega rotation rules with varying degrees of wall kicks, such as Flash Point, Bloxeed, Sega Tetris, and the Tetris Plusseries.
Colors
Games using TGM/Sega rotation generally uses the following color scheme:
I: red
J: blue
L: orange
O: yellow
S: magenta
T: cyan
Z: green
Games
The following games use Sega rotation as their basic rotation:
