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Originally written by Rosti LFC on NSider (with thanks to Sully/CRAIGSS). Moved here and updated.
[edit] What Is A T-Spin?
Tetris DS is not the only game to acknowledge T-Spins, but other games have different criteria for what a T-Spin is. This is what Tetris DS uses to identify a T-Spin:
- The last movement of a piece must have been a rotation, ie. not a movement either downwards or to the side.
- Three of the four corner squares must be occupied by wither other pieces or the wall of the playing field. To try and explain this:
Imagine the four rotations in a 3x3 box like this:
For the rotation to be considered a T-Spin by the game, three of the four corners must be occupied. Here are some examples:
All of these would be classed as T-Spins by the game, and a box would flash 'T-Spin' on the right of the playing field, confirming so.
The fact that the system works like this allows for some moves which shouldn't be T-spins:
As you can see, the piece could have been dropped in place, but this method registers it as a t-spin, and awards extra points/ garbage lines because of it. There are also some rotations where you might expect it to be a t-spin, but it isn't as not enough corner squares are occupied:
[edit] Using T-Spins On Single Player
The only way to get huge scores on marathon and line clear is to exploit the huge bonus points which t-spins give per line over Tetrises. The main two setups which you can use to get points are the double and triple setups:
It is helpful to know these setups and to be able to recognise them. This allows you to make them with improvisation (rather than by following certain setups), converting a possibly awful field into a very beneficial one.
T-Spin triples are pretty useless on their own. While making them it can cause you to stack high around the setup, and once the T-Spin is done, you are left with an awkward and unbalanced playing field. To counter this triples are usually setup back-to-back, to get the greatest return for a messed up playing field.
The main benefit to this setup is that it can allow the use of T-spin doubles indefinitely. In practice however, it is usually not quite that simple. The main shape requires a continuous back-to-back t-spin triple setup (two blocks, gap, two blocks, gap etc.) which is threee blocks away from the wall of the playing field. This shape needs to be built without using S or T blocks, as they are needed to complete the doubles. Here is a basic portrayal of how it works:
