What a Perfect Game of Tetris Looks Like

Tool assisted runs have been made for countless video games, typically created to beat a game as fast as possible. So, what happens when a TAS is made for Tetris? Is it possible to "beat" the game? Let's find out.
Watch the run in full here: • [TAS] NES Tetris "fast...
Greg's extensive StackRabbit showcase: • AI BREAKS NES TETRIS! ...
Videos featured:
Super Mario Bros. TAS: • [TAS] NES Super Mario ...
A Bored God Plays Tetris: • A bored god plays Tetris
Joseph Saelee's CTWC qualifier maxout: • 3 Max-Outs and 2 Lvl 3...
2004 TAS: • NES Tetris in 4:06.07 ...
2006 TAS: • [TAS] [Obsoleted] NES ...
2007 TAS: • [TAS] [Obsoleted] NES ...
2010 TAS: • [TAS] [Obsoleted] NES ...
256 level NES Tetris TAS: • Nes Tetris: level 256 ...
MylesTheGreat's level 29 start Maxout: • MY FIRST LEVEL 29 MAXO...
The 0.0009% calculation is thanks to the work of Fractal161, and a detailed spreadsheet of that work can be found here: docs.google.com/spreadsheets/...
Music (in order):
Battle Assault 3 Featuring Gundam Seed: Track 5 Theme
LEMMiNO - Nocturnal (BGM)
Stevia Sphere: A Sphere Made of Stevia

[@okCobalt]

FYI: For convenience, the timer display for the TAS runs in the video uses in-game time, where the timing runs from the startup of the game until a maxout is achieved. "TAS" timing takes into account the first input (game bootup), and stops with the very last input made by the TAS, which is why the TAS times and in-game times vary by a couple seconds. I figured it was helpful to showcase in-game time as well.

[@caped_crusader4]

sweet

[@drewlop]

I can't process the grammar of this comment; maybe if I were reading more about TAS's but because I haven't been, I can't figure out what that first sentence is supposed to be saying

[@NinjaNezumi]

Downvote because you said chess is not a solved game. It is.

[@gdstuff7666]

DOWN

[@drewlop]

Oh I think I get it now: "TAS runs" is a plural noun in that sentence

[@jr637-1]

That tic-tac-toe robot with the cheat for the win was such a big brain play. How can you compete with that?

[@WaterLemon147]

I burst out laughing when that came up

[@jingxiawu8094]

You can’t

[@Blackfromstickworld]

Cheat for the win before it does

[@ziggyzoggin]

with the tree strategy, its kind of cool how they're on such a higher level of thinking with tetris that they look stupid. "MY GOALS ARE BEYOND YOUR UNDERSTANDING"

[@PeptoAbismol]

tech/strats that look stupid but require high level thinking are my favorites

[@jamesflames6987]

I love the way on old games like this and Pacman, there's not end programmed into the game and it eventually just crashes at a level the developers thought no one would ever get to.

[@biggiemac42]

Hi! Great video but it has some wrong info toward the end about the game crash. The game crashes in a different place on modified roms (including modifications as simple as score uncap!). In the pure vanilla tetris cart, it can be made to crash as early as level 155, which is within 100 lines of the best human game. Stackrabbit played on an uncapped rom, which moved the earliest possible crash to a much more distant level. Tetris gym, where eric played his lines world record, has the crash patched entirely. Additionally, crash even on the vanilla cart can be avoided, as was demonstrated in 2014 by a TAS from quad8/TDrop, and confirmed much more recently by a code deconstruction by Fractal, Kirjava, Kitaru, and others. It requires consciously avoiding certain numbers of line clears on certain levels, which is somewhat hilarious. Not only do you have to play killscreen on awful color palettes, but e.g. singles are not allowed. We are looking into getting the TAS by quad8/TDrop console verified. It ends on level 256.

[@okCobalt]

Thank you for the correction! The script was made before that info was made more public by Fractal and others (Fractal was the one who gave me the revelation that there are ways to either perform the crash very early or skip it entirely), and it's my fault for not amending the script in that manner afterwards.

[@w7u]

lol right now 155 is only 9 lines away from the current wr

[@AmaroqStarwind]

I would love to see a patch that optimizes the game code so that it can check/update player input at a full 60 frames per second, or maybe even faster (like every scanline)

[@dandanthedandan7558]

Imagine a world championship finals where the players are having an endurance run during the glitched colours and the loser is decided on who crashed first

[@AndrewBlechinger]

@@dandanthedandan7558 Stuff like this is why the classic tetris community is debating introducing a line cap for tournaments, purely as a pace of play issue.

[@falquicao8331]

7:05 Technically, an infinite game of tetris is not possible unless you have the ability to manipulate pieces because there exist a long sequence of pieces that forces a top out.

[@gonengazit]

It's possible, it just has probability 0

[@drkn0ckers715]

Well technically the rng of NES tetris is not a perfect uniform distribution on all seven pieces. If I remember correctly certain pieces can only spawn a finite number of times in a row. While this almost surely doesn't invalidate your statement, I can't say for certain.

[@AndrewBlechinger]

NES Tetris does not use the "bag" system that later games use to determine piece sequences. The first two pieces are generated at game start, and each new piece is generated when a piece locks. This is why pausing as manipulation works.

[@adroitbean5440]

Would the RNG manip used by the TAS be able to make sure that combination never happens?

[@boberttheboss8990]

@@adroitbean5440 He said that marathon tetris ai doesn’t use RNG manipulation and without perfectly plotted inputs I’d imagine it’s probably impossible to do rng manipulation on the fly

[@ryanamburgy2791]

It’s a good day whenever cobalt uploads

[@mrhalfbacon]

Cool video! I’ve watching your videos for over a year now and they keep getting better and better!

[@taemien9219]

At 6:22 the StackRabbit achievement says 1.5 Million human possible. 1.5M score will get you like 3rd or 4th place in open tournaments now. Rolling players have pushed what is humanly possible in the last few months.

[@MrBrain4]

Just because a game has randomness does not mean that it cannot be solved. Also, there are different definitions of solved, ranging from "weakly solved" to "strongly solved" which have to do with whether a game result is known, as opposed to knowing the optimal move for all possible game states.

[@Anomaly92]

6:55 - so the game finally breaks at lvl 237? The record makes insane jumps these days and is now at lvl 146, I guess it's totally realistic that someone achieves the final game breaking barrier of this game eventually

[@okCobalt]

There does seem to be a way to reach the game crash much earlier than level 237, something I'll be covering in the new world record analysis in a few weeks.

So there IS a built in line cap! These tetris devs thought about everything!

[@coalbucket9383]

@ game crash is skippable, though very difficult to do from a human

[@EebstertheGreat]

Stackrabbit has an extra digit in the score and other changes which will presumably change the time the crash happens.

[@Chase3141]

It also depends on what hardware you're using. An emulator will crash later than a real NES because the hardware is more powerful.

[@Criggster]

I would love to see a stackrabbit video! Your content is awesome 😎

[@chiri4782]

this video was insanely well made, i'm surprised it doesnt have way more views.

[@gus8696]

Really well done! Super entertaining

[@jorishenger1240]

Amazing video, ive played tetris like 3 times ever but i was hooked the whole time

[@camspianosink]

Very cool breakdown, thank you.

[@goatmin]

YES WE NEED STACK RABBIT

[@ivanplays_games]

No worries, eric will do this within tomorrow

[@ivanplays_games]

*slight year update : Alex T will do this in 2026

[@nicest_tf2_player]

great video. thanks a ton for contributing to this small community

[@seeps9353]

256 is the most important number in all of gaming.

[@aenstreams1998]

Another banger of a vid!

[@user_user1337]

this is truly interesting! thanks so much.

[@dylanconner8167]

That dude's glove technique with the nes controller is nuts

[@TheBronzeSword]

yes, stackrabbit analysis !!!

[@joshuacordasco1610]

great video. well said and well made

[@-chevre-4250]

Great video!

[@taoistflyer]

I'd love to see a more in depth video about stack rabbit, you make great content and you could really make a good video about it.

[@TSERULOGOTH]

GREAT video :D

[@VariantNYC]

that chessboard/4bar idea is an excellent usage of the piece manip 👌

[@rauladdams5709]

I would love to hear more from you about the StackRabbit AI. 👍

[@ieatgarbage8771]

I _think_ most versions of tetris are actually solved due to the limits on the randomness (pieces have to be in the same amount but not the same order). This doesn’t apply to the original, which is completely random. Oh, I guess newer versions still have killscreens, so really anything past that is unsolved.

[@MisterPenguin42]

This. Was. Awesome.

[@ThorkilKowalski]

now that "colors" has been reached, I guess "crash" is the next milestone.

[@zacknicley8150]

Are you sure? [rising inflection]

[@cedricaguilar4501]

Never thought people were speedrunning Tetris

[@E4439Qv5]

Speedrunning high scores of Tetris, anyway. I've lost with a score of 0 in under 5 seconds by spamming the hard drop, and there's no way I was the only one doing that.

[@FatherManus]

I’m surprised this doesn’t have a million views. You should make a video on stackrabbit.

[@EvidentlyFire]

that four tetris clear to max out gave me shivers

[@WannabeMarysue]

I thought this video would explore the playaround TAS shown in the thumbnail. Oh well, it was more interesting for exploring other TASes anyway.

[@Jennn]

So Oddly Satisfying To Watch. I can totally understand how the Tool Writers could endure, watching all that Neatness xD

[@PureNrGG]

I'd love to see you cover the tetris AI! New sub btw 😊

[@videogamechess6422]

Yes make a stackrabbit video. One time I tried to install it and I was too stupid to figure it out

[@huevonesunltd]

Then one day someone will figure out a way to use ACE in tetris to code something that avoids the kill screen

[@BriarLeaf00]

Hey thanks for doing in 7+ minutes what a lot of youtubers would stretch out to like 30 minutes. Much appreciated. Also, can someone clue me in to what the whole controller/ove glove situation is with these top tetris players? What's that setup all about?

[@cuppahotnoodles]

I’m not an expert, but from what I know it’s a technique called “rolling.” Competitors lay the controller sideways on their lap or knee and “roll” or drum their gloved hand against the back of the controller, while keeping their other hand in front of the d-pad. This causes the controller to shake back and forth against their hand, allowing the d-pad to be pressed in rapid succession. This gave an alternative the physically demanding “hyper tap” in a way that was both more efficient and less taxing on the hands.

[@BriarLeaf00]

@@cuppahotnoodles Cheers! Thank you for the explanation, an interesting work around that's for sure.

[@Alexander_Grant]

Absolutely love your videos, found them recently, was watching some tetris stuff after watching the recent CTWC. I do have one criticism, and it's something really minor, but you have a tendency to raise your voice at the end of your sentences, and it sounds similar to that Chills narrator guy. I think if you fixed that, it would improve the quality of the narration quite a bit. Other than that, I've subscribed and currently going through everything else on your channel, looking forward to your next video! I have no doubt you just need that one video to hit the algorithm to blow up.

[@DoubleH313]

Cool video thanks

[@cybergamez1442]

noice, and here i thought that TAS stood for The Amazing Spiderman.

[@gabrielbarrantes6946]

So, stackrabbit was Eric the whole time? 🤣 Nice video

[@adventureoflinkmk2]

Yes, let's go into the jack rabbit

[@alternamasaki429]

nothing beats the perfection of the greatest pro of all time, Todd Todgers

[@ferociousfeind8538]

A slightly modified version of Tetris _is_ a solved game. The modification is that the pieces given to the player are at the discretion of a competing player, making Tetris a two-player game. With this change, Tetris is unbeatable. Many second-player strategies can be employed to achieve this, though the simplest (and one of the most brutally efficient) is giving the player alternating S and Z pieces. This will end the game in under 100 given pieces, I think the number is like 54. Oh, that's not fun? Well then, we'll leave the piece generator alone, and instead state that to beat Tetris you must have a strategy to combat any series of pieces given to you- you must be able to play forever. Because any good random number generator will eventually give you any finite string of results, it will eventually play a fatal strategy an adversarial player would play, and so the game as a whole is unbeatable, and thus it is solved. There are multiple papers on this, lots of nerds do science on Tetris

[@PheseantNetsuke]

fascinating

[@somniad]

fun little thing - tetris can't be played forever! not with true randomness at least - because it's possible to just keep getting s and z pieces in such a way as to make it impossible to deal with; bag-based randomness is better, but can still have impossible situations sometimes depending on the randomness system, whether you can hold, and how much lookahead you get

[@gregorymorse8423]

The idea of solving tetris requires a strategy to deal with a specific uniform random distribution of the shapes along with their entry orientation. The tool assisted speed run of a specific NES game is really quite different, it's not random, full of glitches, etc. So the way this starts with a theoretical cast, then devolves into the specific and practical was a bit misleading. Nonetheless impressive how good the tools have become.

[@Sphendrana]

what's the guy near the end doing with the fabric glove tap on the nes controller? I see it, but I'm a little confused about the hand positioning, and would like to know more about this technique.

[@drfuzzman]

This is the rolling technique. The thumb on one hand applies some pressure to the d-pad, but not enough to cause inputs without the force of the fingers of the other hand tapping the back side of the controller in a single rolling motion.

[@baotan774]

Perfection

[@D9Beats]

New goal: Tetris max out

[@jonathanbaxter2792]

how far can the stack rabbit go with the reaction speed being its limiting factor?

[@skelkankaos]

Is there any in depth videos like this for the Tengen NES Tetris?

[@WalyB01]

stack rabbit is awesome

[@siadurans]

For one sec I thought I was watching a summoning salt video

[@knownas2017]

Oh, hey! A good video! I've had fun TASing Tetris before. Though, I didn't use an Emulator.

[@want-diversecontent3887]

How do you TAS without an emulator?

[@knownas2017]

@@want-diversecontent3887 I Made a TAS for NullpoMino, for pc. TAS means "Tool Assisted Speedrun". I used a tool to assist the "speedrun", therefore TAS. Emulators are unnecessary. But how I did it, I didn't have save states or frame advance- Just slowdown(1 frame per second), and an okay Tetris skill. I know there's Pc emulators, but the one I tried seems to be experimental and hasn't worked for me. The only TAS I've seen with it, is Spelunky.

[@Fvckallofyou1]

Hey, it’s the sequel to the bored god!

[@Geo34]

“AI will take over in the future” the AI in question:

[@Fibero-Fibero69_420]

this is nowhere near to AI💀

[@Geo34]

@@Fibero-Fibero69_420You may have missed the joke.

[@Fibero-Fibero69_420]

@@Geo34 I guess it wasn't a good one, it's also easy to interpret as another random non-speedrunner not knowing what TASes are

[@deleted-something]

crazy

[@medea27]

Two things guaranteed to happen when I watch TAS... a) I'm insanely impressed by the strategies & gameplay possible within the limits of the game code... and b) my blood pressure goes through the roof! 😂 After decades of playing Tetris casually, I can't help having a visceral reaction watching gameplay that hovers on the edge of a 'game over' screen!

[@djupsman]

The I piece def drops more often in these runs than and regular random run imo.

[@loud_laughter]

Dorks.

[@Ara_Arasaka]

Tetris is so interesting

[@06racing]

Stack Rabbit video please.

[@adarshk7484]

pls come back where have you been? 😥

[@okCobalt]

I've been working on videos for a shorts channel for the past few months. I do intend to upload more videos on this channel and am currently working on one, but I don't have a set date for when it will be uploaded just yet.

[@markgoggin4776]

Summoning salt but for tas’s. Me likey

[@PNats-fg4bw]

5:44 why didnt they make the bars vertical? The game would have ended sooner, right?

[@Odrox]

They don't have to end the game. The timer is stopped at the last input of the tas.

[@PNats-fg4bw]

@@Odrox ah, I see

[@behnkeflores7244]

NOW 3 PEOPLE BEAT TETRIS

[@Schniiiiiiiiiiiiif]

cover stackrabbit plz

[@TS_Mind_Swept]

How many kill screens does the game have..

[@officegossip]

Great video once I can mentally block out the repetitive inflection.

[@PanchoKnivesForever]

Just do it. Don’t even need to ask us. JackRabbit video would be amazing. Can’t really say no to Tetris content offers made by the legendary okCobalt. Your videos are amazing!

[@nickinportland]

Lol well that’s it. I’ve hit my nerd threshold on KZbin.

[@pontusvongeijer1240]

Neeeeerd!

[@The_SOB_II]

I don't think you have to enunciate every sentence like it's a surprising headline being read by a newscaster

[@howeverythingends8976]

Would love a video on the AI

[@Fibero-Fibero69_420]

this is no where near to AI💀

[@greggorman5537]

I have a perfect system and can play a game for hours with the hold you can hold off places that would off set it Z on the right or left side the L makes squares on the opposite leaving 2 block space for l peace and anything you have to much of

[@darren8453]

This was great but you need to slow down the presentation of information for mere mortal nerds like me who don't have the background.

[@maverickREAL]

this video reminded me of a dream I had in the dream Strong Bad from Homestar Runner existed in real life but he didn't do anything he did in the series and instead he just got INCREDIBLY good at Tetris and played it basically at machine levels. He got so good he literally beat Tetris, he got a Z-piece that was called the "Done Block" that ended the game with a "thanks for playing" screen when it was placed

[@borstenpinsel]

What on earth is happening at 6:10.... what's he doing?

[@Fibero-Fibero69_420]

Yeah, that's called Rolling, a technique to move pieces fast enough to survive on post-killsceen levels (29+) which uses fingers on the back to hit the controller into a finger on the top, essentially using a giant button. The gloves are to reduce friction and help rolling

[@voo7210]

I say okCoolbalt becous you cool)

[@ebanavorio]

I like your accent, where are you from?

[@keithsinter5611]

Chess and Tetris are not alike. For one, the amount of possible moves is finite in chess and for another, chess is basically solved since you can't win against a AI without either cheating or the AI making "misstakes" to give the player a chance.

[@judaiyuki5597]

time to make a channel where an ai plays tetris forever XD

[@KitchenerLeslie2]

“Perfect” Mario run, doesn’t hit the top of the pole...

[@GamerJP30]

You can't solve Tetris, but it will always solve you.

[@TheLifeOfKane]

For the Record: Bobby Fisher now HATES chess, entirely because chess is NOT unlimited, it is in fact extremely limited. He said instead of learning to play chess and learn to see tactics, people started just playing through pre-established tactics because there was a very finite number of possibilities when playing against another human. Bobby Fisher hates chess... if thats news to you, let that sink in. Tetris on the otherhand has RNGs, and is truly random. Its number of possibile outcomes is truly staggering and only the actual talent can be honed. Chess... You just follow procedure.

[@pascaltomasovic3586]

"in chess every game is unique" lol. you havent seen low elo chess where noobs lose in less than 15 moves and they have happened thousands of times

[@themonsterunderyourbed9408]

Every game of chess is not unique. Chess gets really boring at high levels because most games have already been played.

[@ryanamburgy2791]

He confirmed this over with me. I told him this was true but that he was for the most part right

[@zega126]

0:31 Lmao

[@EebstertheGreat]

I don't understand your calculation for the probability of four consecutive I pieces. Shouldn't it be 1/7 * (1/28)^3? Because the probability of a random piece being an I is about 1/7 on average, and the probability of an I piece following an I is about 1/28. That gives a probability of .00065%. And I don't think this is a hardware limitation. This piece of code deliberately reduces the frequency of repeat pieces.

[@fractal161]

Cobalt's calculation is mostly correct (I believe he typoed a 0.149 that should be 0.139), since he uses more information about the piece selection process. The 1/8 at the beginning is the *piece count* metric, which influences the algorithm. It turns out 4 bars can only occur when the piece count is a specific value. From then, we can use exact transition probabilities to figure out the rest. Overall the explanation behind the math is too tedious for the video but it is correct.

[@fractal161]

Also, this is a bit more nitpicky, but not being able to express a perfect 1/7 probability by itself is arguably a hardware limitation. Obviously the reroll is a deliberate choice but much of the jankiness is probably because the nes is a pain to write code for. These two sides do get muddled though.

[@EebstertheGreat]

@@fractal161 Is there a description of the Tetris RNG that I can find online?

[@netesky1889]

not to be that guy... but chess is a solved game, it is a closed game with finite actions.

[@Rahmations]

When bedwars montetage

[@okCobalt]

what's a bedwars

[@FzeroVaporeon]

700th video like

[@AmaroqStarwind]

5:42 Could have saved a few frames by rotating those pieces.

[@Nickps]

The way TASers time their runs stops at the final input, so from that perspective making the game end sooner would waste a few frames.