Tetris Variations

Tetris has been subject to many changes throughout releases since the 1980s. Newer Tetris games have focused on a trend of pace rather than endurance. Older releases such as Game Boy or NES Tetris offer records according to points. Since the meter for points is restricted to a specific number of digits, these games' records can be "maxed out" by an experienced player. The next big Game Boy release after Tetris, Tetris DX, in marathon mode—comparable to mode A in previous releases—allowed an additional digit for the point meter. Even so, players still maxed it to 9,999,999 points after hours of play. For The New Tetris, world record competitors have spent over 12 hours playing the same game. In Tetris DX and The New Tetris, the new modes sprint and ultra were added. These modes require the player to act under a timer, either to gain the most lines or points in that time. Releases like Tetris Worlds did away completely with point records. This particular game kept records by how fast a certain number of lines could be cleared depending on the level. Critics of Tetris Worlds said it was flawed by virtue of the ability of a piece to hover over the bottom for as long as a player needs.

There are many different modes of play added in recent years. Modes appearing in more than one major release include: classic marathon (game A), sprint (otherwise game B or 40 lines), ultra, square, and cascade.

The field dimension of Tetris is perhaps the least deviated among releases: almost always 10 cells wide by 20 high. Some releases on handheld platforms with small screens have smaller fields; for example, the Tetris Jr. keychain game has 8 by 12, and Tetris for Game Boy has 10 by 18.

Traditionally, blocks spawn within the four most central columns and the two highest rows. The I Tetrimino occupies columns 4, 5, 6 and 7, the O Tetrimino occupies columns 5 and 6, and the remaining 5 Tetriminos occupy columns 4, 5 and 6 (or in some, especially older, versions, 5, 6 and 7). In some more recent games, pieces spawn above the visible playfield.

In traditional games, a level-up would occur once every ten lines are cleared. After a level-up, the blocks fall slightly faster, and typically more points are given. In some newer games such as Tetris Worlds, the number of lines required vary upon each new level. For example, NES Tetris operates at 60 frames per second. At level 0, a piece falls one step every 48 frames, and at level 19, a piece falls one step every 2 frames. Level increments either terminate at a certain point (Game Boy Tetris tops off at level 20) or increase forever yet not in speed after a certain point. NES Tetris will level up in speed until level 29 (due to limitations of the game's engine, pieces are not capable of dropping faster than this), but tool-assisted emulation will show that the level indicator increases indefinitely—eventually leading to a glitch where the meter displays non-numeric characters. Modern games such as Tetris the Grand Master or Tetris Worlds, at their highest levels, opt to drop a piece more than one row per frame. Pieces will appear to reach the bottom as soon as they spawn. As a result, these games have a delay that lets the player slide the piece on the bottom for a moment to help deal with an otherwise unplayable fall speed. In some games, the hover time is regenerated after a piece is moved or rotated.

Soft drops were first implemented in Nintendo releases of Tetris so that pieces would be able to drop faster while not locking as to slide into gaps. The other option is hard dropping, which originated in early PC games such as Microsoft Tetris, a game developed by Dave Edson and bundled with Microsoft Entertainment Pack. With hard dropping, a piece falls and locks in one frame. Newer Tetris games feature both options. Some games have their locking roles reversed, with soft dropping making the pieces drop faster and locking down, and hard dropping making the pieces drop instantly but not lock.

Single direction rotation is an older restriction that has since been ruled out in nearly every new official release by the favor of separate buttons for clockwise and one for counterclockwise rotation. In traditional games, the unsymmetrical vertical orientation I-, Z-, and S-pieces will fill the same columns for each clockwise and counter clockwise rotation. Some games vary this by allowing two possible column orientations: one for counter clockwise and one for clockwise rotations. Double rotation—only seen in progressive clones such as Quadra and DTET—rotates the piece 180°.

One of the features most appreciated by skilled players is wall kick, or the ability of rotating the pieces even if these touch the left or right walls. In the NES version, for example, if a Z piece is "vertically" aligned and falling touching the left wall, the player cannot rotate the piece, giving the impression that the rotate buttons are locked. In this situation, the player has to move the piece one position to the right before rotating it, losing precious time. Proper implementations of wall kick first appeared in the arcade version of Tetris by Atari Games.

Piece preview allows a look at the next piece to enter the field. This feature has been implemented since the earliest games, though in those early games, having the preview turned on made the score increase more slowly.