Marathon is a game mode where the player plays the game either until completing a fixed level, or endlessly. It is the main mode in most Tetris games. Here, players clear as many lines and get the highest score possible. If the player stacks pieces to the top or reaches the goal, the game ends.
In most cases, the level caps at 15 (or 150 lines), but the ending level can go as high as 30.
Marathon in the Tetris Guideline
The Tetris Guideline defines two types of Marathon modes. The variable-goal system was common in the earlier years of the guideline, but since around 2010, it has largely been phased out in favor of the fixed-goal system.
- In the fixed-goal system, each level requires 10 lines to clear. If the player starts at a later level, the number of lines required is the same as if starting at level 1. An example is when the player starts at level 5, the player will have to clear 50 lines to advance to level 6.
- In the variable-goal system, each level requires a specific goal to clear, which is 5 multiplied by the level number. In games after the introduction of the current scoring system, the amount of goal given by a line clear is equal to its base score value divided by 100 and rounded down. Excess goal is not carried over between levels.
Most Guideline games have a speed curve based on the curve used in Tetris Worlds. In this speed curve, the time for a piece to move down by one row is given by the following formula:
Time = (0.8-((Level-1)*0.007))(Level-1)
Though the values produced by this formula have a huge number of decimal places, the following approximate G values retain frame-accuracy and are therefore indistinguishable from the formula.
There is no concrete rule on how to handle the speed curve after level 19. Tetris at tetris.com reduces the duration of lock delay between levels 20 and 30. Some variations on the speed curve have been observed: Tetris DS, for example, offsets the curve by 1 level and rounds the speed values to the nearest frame; Tetris 99's 999 Line Marathon mode expands the speed curve scale further to be gradual in the first 50 levels before quickly speeding up to 20G in the last 49 levels.