Multiplayer Techniques

Non-overstacking Construction
Overstacking can be very dangerous against an agressive opponent. If a player is not able to get down to the garbage efficiently, he'll be overwhelmed by garbage.

In this situation, a player overstacks and takes longer to get down to the garbage.

With the same sequence of pieces, a player can opt to switch the position of the T and the J, resulting in a clean opening for the garbage.

Towering
When facing an ever changing system of garbage, often, a player has to make the field uneven in height to avoid overstacking. Be wary when towering because it's not always productive. If a player is not careful, he may end up severely decreasing his options in tetromino placement.

Alternative Line Clear
To clear garbage efficiently, sometimes, a player needs to clear lines with different methods.

Mis-drop
A mis-drop is nothing more than garbage in disguise. Build over it and clear it as you would normal garbage.

Downward
When a player is starved of I tetrominoes and garbage is coming at a fast rate, he has to depend on other tetrominoes to keep himself from topping out.

If a player is close to topping out, create a funnel for safety.

Easy to grasp? How about these?

Upward
When unable to tetris because of a funnel, fill it up.

Pyramid
Situations like this should be remedied as quickly as possible in a match to avoid future complications.

Overhang
When plagued by an unfortunate sequence of next pieces, an overhang is another form of a scapegoat.

Tetris
BtB tetris is probably the most widely used tactic of them all. A player simply builds up for one tetris. After clearing with an I, a player stacks on top of the foundation for a second tetris.

T-Spin Single
T-spin singles are the easiest to spot and to exploit in multiplayer. Not utilizing them will only put you at a disadvantage against an opponent who does. In Tetris Worlds, T-spin singles with the T tetromino's flat side against the wall don't send garbage, but in Tetris DS, they do.

If a situation is not readily available, create one if you don't already have a BtB chain going.

This one works even on Tetris Worlds because the T's back is against other blocks, not the wall:

T-Spin Double
T-Spin Doubles, when combined with tetrises, produce one of the most deadly combinations in multiplayer.

The article ST stacking describes a stacking method that uses several consecutive T-spin doubles. Though designed for single player, it can also prove useful as an opening in multiplayer.

Offensive
A player should be agressive when the opportunity arises. Do not sit and counter garbage. Let yourself recieve garbage and send it back. You want to send the most garbage as possible. Often, it's better to tetris after the opponent because they will not be able to counteract the garbage, either accidentally or intentionally.

If you have a chance to BtB in a short time period, don't pass it up. The more time you give your opponent between a BtB, the more likely he will have formed a plan for the upcoming garbage.

Defensive
When nearing a top out, counter the garbage as best as you can. Your opponent will not recieve extra ammunition and will have to build his own tetrises. Do not waste time making many singles. Most of all, remember not to overstack.