Playfield
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The playfield is the grid into which tetrominoes fall, also called the "well" (common in older games) or the "matrix" (especially in more recent Tetris brand games). The playfield is surrounded by a frame called the tetrion, which controls the overall behavior of tetrominoes.
The vast majority of tetromino based game use a playfield 10 cells wide and between 16 and 24 cells tall, with most Guideline-based games using a visible height of 20 cells. Notable exceptions include the following:
- Abandoned Bricks: 9 w
- Gnometris: 11 w until mid-2007; then 14 w
- Tetrinet: 12 w
- Tetris Jr.: 8 w
- Tetris Game Watch: 6 w
- Tetripz: 11 w
- Tetris (NES, Tengen) Cooperative Mode: 12 w
- ТЕТРИС SEMIPRO-68k: 4-32 w (customisable)
- TAP Doubles Mode: 14 w
- Tetris Party Doubles: 20 w
- Full HD Tetris more: 320 w
Columns are conventionally numbered from left to right, and rows from bottom to top.
Vanish zone
The vanish zone is the region above the ceiling of the playfield. There are two ways for blocks in the stack to enter the vanish zone: either being pushed up into the zone due to garbage lines, or by locking a piece partially in the vanish zone (most games do not allow pieces to lock fully in the vanish zone). In games with a solid ceiling (such as Tetris (Sega)), blocks cannot enter the vanish zone due to rotation, but may still be able to due to garbage.
Blocks that enter the vanish zone may be truncated or enter a buffer zone depending on the game. The vanish zone may or may not be visible.
Some games, usually those with a visible vanish zone, spawn pieces inside the vanish zone. The Tetris Guideline requires that pieces spawn at least partially inside the vanish zone (the exact rows differ between versions).
Stack truncation
Games may simply truncate the part of the stack that enters the vanish zone. If the player then clears lines the blocks that were truncated will no longer be present.
This is most often seen in games that use partial lock out (i.e. top out if part of a block locks inside the vanish zone).
Buffer zone
Games may have a buffer zone above the ceiling to store blocks that enter the vanish zone. In these games, tetrominoes may land and lock partially within the vanish zone; they reappear once a line is cleared below them.
For example, the modern Tetris Guideline specifies a visible playfield 10 blocks wide by 20 blocks tall and a buffer zone above the playfield of 20 rows in height, and the tetrominoes spawn in rows 21 and 22 at the bottom of the buffer zone. This is so that a player with no blocks in the vanish zone can survive 20 rows of garbage sent at once.
Other games may have smaller buffer zones. In these cases, blocks that pass the top of the buffer zone are usually truncated (see above).
- Tetris The Grand Master and its sequels use a 1-row buffer zone.
- Lockjaw uses a 4-row buffer zone.
- Jstris uses a 1-row buffer zone, despite otherwise being guideline-compliant.
Many games hide the entire buffer zone, though some games allow part of row 21 to be visible.
Other behaviour
Tetris (Game Boy) and Tetris (NES, Nintendo) are both notable for having buggy behaviour in relation to the top visible row, in each case causing blocks to be duplicated in some way.