Line clear

The object of Tetris is to last as long as possible before the screen fills up with tetrominoes. To do this, you must assemble the tetrominoes to f工控机 茅台酒 二锅头 防伪标签 热转印机 水晶像 奖杯 干洗 数码快印 硒鼓加粉 塑料颗粒机 防伪 防伪技术 高新技术企业认定 北京洗衣公司 服务器机柜 空气净化工程 国际速递 国际快递公司 国际快递 梯具 节能节电 冬令营 石材翻新 电器维修 北京公司注册 制冰机 电脑回收 代开发票 不干胶 机打发票 电缆桥架 电缆桥架 北京货架 航空货运 会议服务 小升初 梅兰日兰UPS 口语 Dell服务器 再生塑料颗粒机 灯光音响 二手电脑回收 热水器维修 环氧地坪 IBM服务器 工商注册 IBM服务器 北京航空货运 北京写字楼 动画制作 orm one or more rows of blocks that span the entire playing field, called a line clear. When you do so, the row will disappear, causing the ones above it to settle.

Single
A single is the act of clearing one line at a time:

Double
A double is when two lines are cleared at once:

Triple
A triple is three lines cleared simultaneously. Most games allow only I, L, and J tetrominoes to complete a triple, but newer games with SRS allow S, Z, and T tetrominoes to twist into seemingly impossible positions.

Tetris
A tetris is four lines cleared simultaneously. In most games, this can only be done with an "I" tetromino.

Hurdle / Split
In Tetris DS mission mode, the act of clearing two or three lines separated by one or more rows with gaps is called a hurdle. In the 1998 Sega Tetris, this move was called a split and it launched a special attack in VS mode. Any tetromino that can complete a triple can complete a hurdle:

Back-to-Back
Back-to-Back clears are any combination of two or more "difficult" line clears without an "easy" line clear between them. The recent games Tetris Worlds and Tetris DS consider a 4-line clear ("tetris") or a T-spin line clear to be difficult. In certain Tetris game modes, you can earn extra points or deal an additional line of garbage by clearing Back-to-Back. All types of "difficult" clears share the same state variable. For example, a player can clear a line with a T-Spin Single using the T tetromino, then clear four lines with an I tetromino, still earning him a Back-to-Back tetris.

Combo
A combo refers to making a line clear with one piece and sequentially making another clear with the next piece, and so on. Lacking in recent games, developers experimented with the concept in TGM and Magical Tetris Challenge, both released in 1998.

Line clear gravity
After a line clear, the blocks above the line move down. How they move down depends on the game.

Naive
Most Tetris games use naive gravity. Here, the blocks above a cleared line move down by exactly the number of cleared lines below them. This can often leave floating blocks, unconnected to anything, after a line is cleared. Most tetromino based games use naive gravity.

Sticky
The playfield is divided into connected segments using flood fill. Any blocks that are adjacent horizontally or vertically are marked as one segment, that is, they are treated as having "stuck" together. Each segment falls independently until it meets the floor or another block. Additional line clears may result. Games that use sticky gravity:
 * Super Scope 6 Blastris A
 * Tetris Blast and Bombliss
 * The Next Tetris (modifies rule such that only blocks of a single color can form a segment)
 * Re-released as Tetris Worlds Sticky
 * Lockjaw: The Overdose

Cascade
When each piece locks, its connections to other blocks in the piece are stored. After lines are cleared, each piece is marked as a separate segment, and then each segment falls independently until it meets the floor or another block, as in Sticky. Games that use cascade gravity: Non-tetromino games:
 * Tetris 2 (Tetris Flash)
 * Quadra
 * Tetris Worlds Cascade and Fusion
 * Tetris DS Touch
 * Dr. Mario

Delay
Some games impose a line clear delay after each piece that completes one or more lines and/or a line gravity delay every time blocks move down by one row. For example, Tetris The Grand Master and Tetris DS wait 400–700 ms. In games with a large line clear delay and scoring based on play time, it is to the player's advantage to make multiple lines at once (triple or tetris) so that less time is spent in line clear delay.