Back-to-Back

Back-to-Back (BtB) or Back-2-Back (B2B) clears are any combination of two or more "difficult" line clears without an "easy" line clear between them.
The recent games Tetris Worlds and Tetris DS consider a 4-line clear ("tetris") or a T-spin line clear to be difficult.
== Recognition ==
Back-to-Back Recognition in Guideline Games
Clear Type 	Recognition
Single 	No
Double 	No
Triple 	No
Tetris 	Yes
T-Spin Single	Yes
T-Spin Double	Yes
T-Spin Triple	Yes
BtB bonus	
Tetris	
Place J	
BtB Tetris
In the above diagrams, BtB is recognized for the second tetris line clear because the line clear right before was also a tetris. The J tetromino placement did not clear any lines and, therefore, does not break the BtB chain.
T-Spin → Tetris	
 EZ TSS	
BtB Tetris
Tetris → T-Spin	
Tetris	
BtB EZ TSS
All types of "difficult" clears share the same state variable.
For example, a player can clear a line with a T-Spin Single using the T tetromino, then clear four lines with an I tetromino, still earning him a Back-to-Back tetris.
No BtB bonus	
Tetris	
Double	
Non-BtB T-Spin Single
Here, BtB is not recognized for the T-Spin line clear because the double line clear broke the BtB chain.
BtB bonus	
Double	
Tetris	
BtB T-Spin Single
The above shows that BtB is recognized for the T-Spin line clear because the line clear right before was a tetris.
== Reward ==
In certain Tetris game modes, you can earn extra points or deal an additional line of garbage by clearing Back-to-Back.
Category:Scoring Systems