A maxout is when a player reaches the game's score cap and can no longer earn points as a result. This is also known as a counter stop (カンスト kansuto).
Maxouts by game
Tetris (Sega) was the first official Tetris game to have a defined score cap, set at 999999. By January 1989 the first maxout had been achieved on Easy difficulty by SPREAM-DIG.
In February 1989 SPREAM-DIG repeated the feat on Normal difficulty, and by March maxouts had been recorded on at least 10 different machines. Subsequently the focus switched to reaching the maximum score in the fewest lines, and by August maxouts had been recorded within 600 lines on both Easy and Normal.
The discovery of the power-on pattern allowed players to achieve faster maxouts by planning line clears in advance, ultimately leading to a route that could achieve a maxout in under 100 lines.
Flash Point and Bloxeed have the same maximum score. It is said that Bloxeed was maxed out at its location test, leading the developers to increase the game's difficulty.
The Sega Ages re-release gave the player the option to change the maximum score to 9999999. Known maxouts include one by 777 achieved in 2019.
Tetris (Game Boy)
As with the Sega arcade version, the maximum score is 999999.
It is not known when the first maxout occurred due to the difficulty of score tracking before the Internet, but given the calibre of players it is hard to envision it not occurring in 1989 or 1990. A video exists dating from 2006, while J.O's high score page has reported a max out score going back at least to 2004.
Tetris (NES, Nintendo)
The maximum score is 999999. Because of the game's unique speed curve and levelling system, maxing out the Nintendo NES version requires not only survival skills but also line clearing efficiency, as it is nearly impossible to score significantly after reaching level 29.
The PAL version has a different speed curve, and as a result, no known maxout exists. The current record as of December 2018 is 758,360 by Joseph Saelee.
Other games with reachable score caps
Games with maximum score 99999
Maxed out by Koryan.
Games with maximum score 999999
All of these have been achieved and videos exist. These are considered relatively straightforward.
No known maxout exists. A maxout would require a significant number of lines cleared at level 29 speeds, which is not impossible (games with nearly 100 line clears at level 29/30 exist).
The gameplay of Tetris S is almost identical to Tetris (Sega), and the game has the same maximum.
Games with maximum score 9999999
Maxout scores have been attested. Known maxouts include a game by Koryan in 2813 lines in 1998.
Games with maximum score 99999999
According to an interview with one of the developers of Tetris (WonderSwan Color) a person left their PlayStation on for a year in order to reach a Tetris game's maximum score, but which game it was (Tetris X or The Tetris) is not specified.
Maxout scores have been attested.
Maxout scores have been attested in Endless mode.
Games with maximum score 100000000
The game displays the score as いちおくてん in hiragana when reached ingame, and as 100000000 on the high score table.
Games with maximum score 999999999
It is unknown if this score has been reached legitimately. A TAS exists that reaches the maximum score in one stage.
- Tetris (WonderSwan Color)
It is unlikely that this score has been reached legitimately due to the incredibly large number of lines that would be required (over 220000 if no perfect clears are scored), but a TAS exists that takes advantage of perfect clear bonuses.
Games with maximum score 2147483647
The game will not count the score event that takes it above 2^32-1, which means the game may stop at a slightly lower score. It is unlikely that this score has been reached legitimately due to the incredibly large number of lines that would be required (approximately 50000 if only Tetrises are scored).
Games with score rollovers
Both the Atari arcade version and the Tengen NES version roll the score over after 999999. For the Atari arcade version, since score is retained between credits it is straightforward to reach 999999 by credit feeding. The Tengen NES version, on the other hand, rolls the score over to 100000 after 999999. Many players have been able to roll over the score in that version several times.
Tetris (Microsoft Entertainment Pack for Windows) uses a signed two-byte variable for score, and hence rolls over to -32768 after reaching 32767.
The arcade version of Tetris Plus rolls over at 1000000. This is in contrast to the console ports which stop at 999999.