Player on the left is going for the so-called
Double Triple Cannon Setup. It's an opener that gives you opportunities for a T-Spin Double and a T-Spin Triple:
Aligning it to the side like he does cleanly leads into a
four-wide well you can combo off of. In modern Tetrises, especially versus mode, T-Spins yield bigger rewards for your effort than Tetrises, and, if you can sustain them, so do combos.
Look at the respective garbage tables:
As you can see, a T-Spin Double sends four lines of garbage for two lines cleared — more than the Tetris sending four for four cleared — and the T-Spin Triple sends a whopping six. Those two back to back send 10! Working with the resulting four-wide well and comboing will send even more.
These things are mainly possible thanks to modern
Tetris guidelines. The
randomizer is standardized to be more predictable, so you can actually plan out your strategy a bit more, you get a hold function to further deal with randomness but also allow for more consistent setups like doing two T-Spins back to back, and plenty of the movements done to set up openers and keeping combos up rely on the
Super Rotation System that defines consistent ways to rotate blocks, even into wonky spaces. I know a lot of this sounds insane compared to the comforting simplicity of the Game Boy Tetris most of us grew up with, but I really think it adds a ton of depth and strategy to the game that reward skill and experience with the systems.