Tetrimino colors are as follows.
Cyan I
Yellow O
Purple T
Green S
Red Z
Blue J
Orange L
In versions that use monochrome screens, or when hardware limitations disallow all colors to be used, the Tetriminos should have distinct hues and patterns to differentiate themselves.

The logo may not have its t-tetrimino split into 4 minoes.
The logo may not be sheared or skewed.
The logo must be 2D.

Game must include a song called Korobeiniki. This must be the default song.

Recognition and rewarding of T-spin moves. Conditions vary between guideline versions.
2005 / 2009: 3-corner T
2006: 3-corner T no kick

So-called 7-bag Random Generator (also called "random bag" or "7 system")...

"Hold piece": The player can press a button to send the falling tetrimino to the hold box, and any tetrimino that had been in the hold box moves to the top of the screen and begins falling. Hold cannot be used again until after the piece locks down. Games on platforms with fewer than eight usable buttons (such as the version on iPod) may skip this feature. The combination of hold piece and Random Generator would appear to allow the player to play forever. It must be enabled by default.