How Do Wall Kicks Work In Tetris Friends

tetristetris-battle

I am trying to program a Tetris clone based very closely off of Tetris Friends 2 Player Battle mode.

Is anyone very familiar with how wall kicks work in this game? Or know where to find reference material on the subject?

I have read up on SRS and DTET, but unless I am mistaken neither of them perfectly describes how wall kicks work in Tetris Friends (rotation matches SRS identically when not considering wall kicks).

One particular behavior that has been confusing me is how Tetris Friends handles situations where either a kick upwards or to the side might be appropriate. Tetris Friends behaves like this with the line piece in this case:

 Before          After
........        ........
........        ..X.....
..XXXX..        ..X.....
....0...  --->  ..X.0...
...00...        ..X00...
...00...        ...00...

When I would have expected one of the following:

Kick Left      Kick Right
...X....        .....X..
...X....        .....X..
...X....        .....X..
...X0...  --->  ....0X..
...00...        ...00...
...00...        ...00...

Can anyone explain this behavior? Even if Tetris Friends has a strange and unique wall kick system, I'd still like to match it as closely as I can. Is anyone familiar with it?

Best Answer

With SRS, all pieces follow the same kick table except for the I-piece.

What you describe happening is exactly how SRS is supposed to work. In either case, rotating left or right will have the same effect here. Going from the original state (state North) and rotating right will first try no kicks. The piece overlaps and tries the next kick offset, -2, 0, which shifts the piece left two columns.

If you try to rotate left, the natural rotation is tried, fails, and the next kick, -1, 0, is tried and works, the piece moves left once. Because the natural left rotation moves the piece left already, it ends up in the same position as a right rotation.

This while not important to your question does bring up a left bias in the I-piece rotation, that isn't seen with the other pieces.

The reason these rotations were chosen is kind of a side effect of how SRS works. With SRS, all rotations are reversible. This means when you rotate and a piece kicks, you can always rotate the other direction to get yourself out. These kicks are just meant for the piece to be able to rotate off of a wall, but the side effect is the reverse (what your example is) has a weird behavior.

Related Solutions

Tetris Difficulty

As far as I know (and I've done quite a bit of reading about Tetris lately), no official version of Tetris changes its piece-selection method as the game goes on.

Assuming you're asking about the NES version, the only difference as the levels progress is the speed that the blocks fall at.

Here is the falling speed for the levels, in the number of frames it takes for each piece to drop one cell towards the bottom. The game runs at 60 frames/second, so a value of 60 would mean it moves down one cell per second, a 6 is 10 cells/second, etc.

  Level    Drop speed
         (frames/line)
     00            48 (0.8 s)
     01            43 (0.72s)
     02            38 (0.63s) 
     03            33 (0.55s) 
     04            28 (0.47s) 
     05            23 (0.38s)
     06            18 (0.3 s) 
     07            13 (0.22s)
     08             8 (0.13s)
     09             6 (0.1 s)
  10-12             5 (0.08s) 
  13-15             4 (0.07s)
  16-18             3 (0.05s)
  19-28             2 (0.03s)
    29+             1 (0.02s)

(source)

For completeness, the randomizer always works as follows:

Pick a (pseudo)random number from 0-7, representing the 7 possible pieces and one "dummy number" (7). If it comes up as 7 or the same number as the previous piece, go to step 2. Otherwise, give the piece represented by the chosen number.
Pick a (pseudo)random number from 0-6, and give the piece represented by the number.

So there's a lower-than-normal chance of getting the same block twice in a row, but that's about it.

What strategies are critical to winning a Tetris DS tournament

In no particular order:

Ability to form T-Spin opportunities between (or instead of) Tetrises; this will let you keep a Back-to-Back chain going if need be
Remembering that you're in it to win it, not score big, so keep your stack at a maintainable level, usually below half the screen
Focus not only on finding great plays, but using garbage to your advantage; it's remarkably easy to turn a row of trash into a T-Spin Double opportunity
Keep your stack even and know when to go into emergency clearing mode. Avoid sharp towers like the plague because the banana peels will ruin your day.

Number 1 is important because if you can T-Spin fast, you can completely ignore Tetrises for garbage-sending. It also helps for #3 when you need to clean up garbage; it's an easy way to get something back.

Two is important because a T-Spin Triple or Tetris back-to-back will send you up six or so rows, which can easily screw you over if you're already high up.

Other than that, just be fast and don't lose your cool.

Best Answer

Related Solutions

Tetris Difficulty

What strategies are critical to winning a Tetris DS tournament

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