Tetris 99

Tetris 99 is a game for the Nintendo Switch that puts 99 players players against each other. It's free to play, but requires the paid Nintendo Online Service, and has a DLC pack for USD$9.99, titled "Big Block DLC."

Details

 * Players complete lines and combos, as per the norm, in which are then sent to other players in the match.
 * Players keep going until they lose and drop out, reducing the amount of players from 99 to 1.
 * After the match is over, the player gets Experience Points, and after enough Experience Points, levels up.
 * The game also gathers details from the matches and totals them in a stats area.

Modes
So far there's only 1 mode in the standard game: the name-giving Tetris 99 mode. The Big Block DLC includes two new modes: Marathon (150 lines or 999 lines), and COM Battle (battle against 98 bots). Data mining has shown that the game may receive a new mode in the future, called Team Battle (2 giant teams battling each other).

Battle Royale
The marketing strategy of Tetris 99 was based on its similarities with the battle royale sub-genre.


 * The game starts with 99 players and the goal is to be the last player alive. The number 99 is known from many other battle royale games.
 * In battle royale games, players have to collect some gear or take them from any killed enemies to increase the chance of winning. It's badges here which function as a damage multiplier.
 * The combat area in battle royale games decreases over time to ensure the end of a game. Here, the gravity increases over time, making the survival harder.

Singleplayer in heart
Tetris 99 brought attention to multiplayer like no other Tetris game before although it resembles singleplayer:


 * Like in Marathon, gravity increases over time. The speed increases in general: softdrop speed is increased with gravity, and the garbage insertion delay becomes shorter.
 * The long garbage cancellation period means that there's a lot of time to prevent the garbage from entering the playfield. Additionally, inserted garbage can often be cleared easily because the column of the garbage hole barely changes. So, there's often no garbage in the playfield, at least in case of good players.
 * Opponents are anonymous until the end of the game, and it's hard to follow their moves because their tiny playfields are updated about five or six times a second. Additionally, the current target's playfield is covered by a target marker.

The attention majorly also comes from the fact that Tetris 99 is more beginner-friendly than any other multiplayer game:


 * The free-to-play nature means that a lot of inexperienced players tried it out which means a rather low average skill in the userbase.
 * Eliminated players can start a new game immediately - they don't have to wait for the other players to finish the game to play again.
 * The clean garbage and the long garbage cancellation delay makes survival easier in early-game. However, huge garbage spikes are pretty common in lategame.

Garbage Insertion
There's a meter on the left side of your playfield showing pending/incoming garbage lines, i.e. lines sent by your opponents which weren't inserted in your playfield yet. If there're incoming garbage lines, then your attacks will be used to cancel/counter them instead/before sending lines to your opponents.

Tetris 99 uses a 3-step insertion algorithm: The lines from the first incoming attack appear in the meter as yellow blocks. After a while they turn red (2.5 seconds after they have turned yellow, 1.5 seconds in the top 50, and 0.5 second in the top 10), and eventually they'll be red flashing (taking the same amount of time), if still not cleared. Red flashing signals the last chance to clear the incoming lines. However, garbage will not enter your playfield, as long as you clear at least one line with each piece placement ("garbage blocking" during combos).

If there are lines from multiple attacks (from either one opponent or multiple opponents), then the later lines will appear as grey blocks in the meter. Grey blocks will stay like that as long as the previous attack wasn't received or entirely canceled - in which case they become yellow and start their insertion timer. Note that a player can never have more than 12 pending lines in the meter; the surplus will be discarded.

Badges
Badges are the rewards for getting "KOs". If a player tops out, the last inserted lines determine the player who scores the KO. The KOing player receives one badge PLUS all badges owned by the topped out player. So, the sum of all badges usually corresponds to the amount of eliminated players. However, it's also possible that the sum of all badges is smaller than the amount of eliminated players, e.g. if two players top out each other.

Badges work as an attack multiplier. A player with 100% attack boost will send twice as many lines compared to 0% attack boost. The attack boost multiplier can be either: 0% (no change), 25% (1.25x damage), 50% (1.5x), 75% (1.75x), or 100% (2x) depending entirely on the amount of badges a player has collected in the course of the game. 25% requires 2 badges. 50% requires 4 more badges than 25%, thus 6 badges in total. 75% requires 8 more badges than 25%, thus 14 badges in total. Each damage boost requires roughly twice as many badges as the predecessor. After the damage has been multiplied, it is rounded down. 

Targeting
The player has 5 options:


 * Randoms: Selects a random opponent (may prefer opponents with a higher level). This is the default option. It's the least useful targeting option.
 * Badges: Targets a player with a high badge count. It's not so useful in the beginning but later on it may help to get some badges or getting rid of strong rivals.
 * KOs: Targets a player who is near the top. It can kill some people who are close to death but it can also backfire when hitting a 2/3/4-wide combo player or even worse, someone using the KO-bait strategy.
 * Attackers: Targets everyone who has recently attacked you (playfield linked with a yellow line). It's the best defensive targeting strategy. However, any damage that you send out will be split evenly between the players targeted.
 * Manual: Attacks a manually selected opponent. Requires a lot of screen-watching to select a good target. Players usually don't have the time for that.

Line Sent Table
The following tables list the amount of lines sent by a line clear.




 * Single means clearing 1 line at once, Doube 2 lines at once, and so on. Singles are the only line clears that may not send any lines.
 * Combo means clearing at least one line with several pieces in a row. The second consecutive line clear increases the combo counter to 1, the third to 2, and so on. Combos send a huge amount of lines in Tetris 99 but also suffer a little from the long line clear delay (as you usually make Singles or Doubles during a combo).
 * A T-Spin is done by spinning a T piece into a location where at least 3 corners are filled of the 3x3 surrounding box of the T piece's final location.
 * A Mini T-Spin is a T-Spin where and where the T piece faces towards an empty corner in its final location. However, a spin that shift the center 2-rows up-/downwards and 1-column-sidewards will count as a regular T-Spin, even if one corner is empty (e.g. see STSD).
 * Back-to-back (b2b): A T-Spin line clear or Tetris receives this bonus, if the most recent line clear was also either a T-Spin or Tetris. Mini T-Spins are only good for keeping the back-to-back bonus - without that bonus they just send as many lines as an arbitrary line clear which clears the same amount of lines.
 * Perfect Clear means reaching an empty board. Perfect Clears are very weak in Tetris 99.

Multiple Attackers Bonus
Usually, the amount of sent lines just depends on the quality of a line clear plus the badges' attack boost mutiplier. However, the game adds a flat amount of lines on top of it depending on the amount of targeters (recent attackers, playfields linked with a yellow line). The Multiple-attackers bonus even receives the percentual bonus originating from badges.

Usually, a Single doesn't send any lines, except during a combo. However, this flat bonus can make Singles the strongest attack in the game - if you measure it in sent lines per cleared line. The KO bait strategy relies on this fact: Stack very high, leave a column empty in the middle. Once you are at the top, clear some Singles without downstacking. Opponents using the "KOs" target option will usually begin to target you - 6 targeters will make each Single send 9+ lines. Combine this with the "Attackers" target option and you will send a huge amount of lines which will earn you some KOs.

Sent Calculation

 * Sum up the corresponding numbers from the Line Sent Table. For example a back-to-back Tetris is worth 5 lines or a 1-combo-Double is worth 2 lines.
 * Add the Multiple Attackers Bonus. For example add 3 lines, if 3 yellow lines.
 * Factor in the Badge Attack Boost multiplier. This bonus is rounded down. For example, 7 lines + 50 % bonus = 7 + floor( 7 x 0.5 ) = 7 + 3 = 10 lines.
 * Cap the result at 20 (never send more than 20 lines). Also note that your opponents will never receive more than 12 lines (12 is the maximum for pending lines). Thus more than 12 is only useful when using a part of it for canceling incoming garbage.

Gravity
Gravity in Tetris 99 does not behave the same as other Guideline games; it uses a lookup table for the "seconds per line" duration. Tetris 99 uses frame counts instead of seconds, presumably to make it easier for the game server to deal with. When a piece begins falling, a "counter" begins counting the number of frames that have elapsed in the game (the game runs at 60 frames-per-second). Each time the counter increases by 1, the game calculates the current level with the equation below. If the counter equals or exceeds the framecount associated with the calculated level, the counter resets, and the piece will fall by one line.

The game begins at level 1, spending 60 frames for every line. It stays that way all the way until the 50th player has been K.O.'d. When that player has been K.O.'d, they send a "message" to the game server, describing the point in time that they died in. The server then sends the same information to the remaining players in the game. When another player "hears" this message from the game server, the player visibly is K.O.'d on the screen, and a timer begins counting up from the point in time the player said they died at. The timer does not begin when the player is "visibly" K.O.'d.

Once the starting point of the timer has been established after the 50th K.O., the current level will increase based off of the time that has elapsed. 10 seconds after it begins, the level switches to 2, changing the framecount for a falling piece to 50. 20 seconds after the level switched to 2, it will increase to 3, dropping the frames/line to 40. 20 seconds more, and the level increases to 4, and so on. The level will max out at 11, where the active piece will fall one line each frame. This is why you may find the game speeding up while you're maneuvering a piece on the playfield. Additionally, holding the soft drop button does not speed up the gravity by a factor of 20. The game uses a separate lookup table for the current level, and the frames/line for a soft drop.

Tetris 99 will calculate the current level by plugging in the total elapsed time of the timer, that began at the 50th K.O., into the following equation: where max chooses the largest of the two values.
 * max(1, floor(seconds + 30) / 20)

