Tetris Guideline

The Tetris guideline is the current specification that The Tetris Company enforces for making all new (2001 and later) Tetris games alike in form. A mode labeled "standard" or just plain "Tetris" will adhere to the Guideline more closely than other modes.

Current rules include:
 * 22x10 cell playing field
 * Tetromino colors
 * Cyan I
 * Yellow O
 * Purple T
 * Green S
 * Red Z
 * Blue J
 * Orange L
 * "Bag" randomization of tetrominoes
 * Tetrominoes are generated 7 at a time as a permutation. (There are 5,040 different such permutations.) This means that only 12 tetrominoes can come between one I and the next I, and a run of S and Z tetrominoes is limited to 4.
 * Tetromino spawn locations
 * The I and O spawn in the middle columns
 * The rest spawn in the left-middle columns
 * The tetrominoes spawn horizontally and right-side up.
 * Tetromino rotation and lockdown behavior (see SRS)