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Binary Tetris -

Tetris Clone -

A simplified variant of the classic tetris game done in less that 140 bytes of JavaScript.

Example Layout


Play the demo at and feel free to edit the source!

More Information

The main logic to move blocks, detect collision, assign new blocks, remove full lines and render the layout are included. Excluded are keyboard controls and the final rendering.

This version is heavy based on binary numbers and bit shift operators. I had to limit the board size to 5x6 (30 bits), because JavaScript converts numbers to 32-bit integers when using bitwise operators. The two left bits are later uses to add the correct padding when dealing with numbers that start with "0".

Basic Concept

The Board

                  00000         .....
798               11000   =>    ##... 
                  11110         ####.

The Block

3                 00011  =>     ...##

Checking for Collision

                  00000         .....
798&3 = 2         00000  =>     .....
                  00010         ...X.

Moving the Block at X Axis

3 << 1 = 6        00110   =>    ..##.

Moving the Block at Y Axis

                  00011         ...##
3<<10 = 3072      00000   =>    .....
                  00000         .....

Combining Block and Board

                  00011         ...##
798|3072 = 3870   11000   =>    ##...
                  11110         ####.

Find full line (using base 32)

                  00011         3
3999              11100   =>    s
                  11111         v

For more information

See the site for a showcase of entries (built itself using 140-byte entries!), and follow @140bytes on Twitter.

To learn about byte-saving hacks for your own code, or to contribute what you've learned, head to the wiki. is brought to you by Jed Schmidt, with help from Alex Kloss. It was inspired by work from Thomas Fuchs and Dustin Diaz.

function (
a, // current board
b, // current block
c, // current position
d, // new block offset for position
e // placeholder: the layout to return
d += c, // add offset to position
e = a | b << d, // render layout based on board and moved block
d < 0 | a & b<<d // check if block touches bottom line
// or if block collide with board ...
&& ( // ... if so ...
a = e = // assign new board and layout
parseInt( // convert back from base 32
( a | b << c ) // get board based on last position
.toString( // convert board to base 32 (2^5)
d = 32 // reset block position to top (32)
.replace(/v/, ""), // remove filled line ("v" = 11111)
d // base 32 (2^5) for parseInt
b = new Date % 2 ? // generate new block for next round
1 : // single "#" (1 => 1)
3 // double "##" (3 => 111)
[ // the final return
a, // new board
b, // new block
d, // new position
e // final layout to render
function(a,b,c,d,e){return d+=c,e=a|b<<d,d<0|a&b<<d&&(a=e=parseInt((a|b<<c).toString(d=32).replace(/v/,""),d),b=new Date%2?1:3),[a,b,d,e]}
Version 2, December 2004
Everyone is permitted to copy and distribute verbatim or modified
copies of this license document, and changing it is allowed as long
as the name is changed.
"name": "tetris",
"description": "A variant of the classic Tetris game.",
"keywords": [
<style>body{ font-family: monospace; font-size: 20px}</style>
<div id="output"></div>
var t =
function(a,b,c,d,e){return d+=c,e=a|b<<d,d<0|a&b<<d&&(a=e=parseInt((a|b<<c).toString(d=32).replace(/v/,""),d),b=new Date%2?1:3),[a,b,d,e]}
// Controller and Display
var out = document.getElementById("output");
var board = 0,
block = 3,
position = 32,
function update(offset){
var txt = "",
result = t(board,block,position, offset);
board = result[0];
block = result[1]
position = result[2]
display = result[3];
display = ( 1<<30 | + display ).toString(2);
for(var i=1; i<31;i++){
txt += display[i] == "1" ? "#" : ".";
if(i%5 == 0) txt+= "<br>";
out.innerHTML = txt;
onkeydown = function(e){
var offset = 0;
switch (e.keyCode){
case 37: offset = 1; break;
case 39: offset = -1; break;
case 40: offset = -5; break;
var speed = 1000;
function loop(){
setTimeout(loop, speed-=5);

tsaniel commented Jan 27, 2012

Binary Tetris! Once again @aemkei makes amazing stuff!
(Sorry that I'm being tired, maybe I'll dig into it tomorrow).

tsaniel commented Jan 27, 2012

Save 1 byte.
function(a,b,c,d,e){d+=c,e=a|b<<d,d<0|a&b<<d&&(a=e=parseInt((a|b<<c).toString(d=32).replace(/v/,""),d),b=new Date%2?1:3);return[a,b,d,e]}

By the way, the snippet has some bugs.

And what about replacing b=new Date%2?1:3 with b=new Date&2|1?


aemkei commented Jan 27, 2012

Nice reordering!

I know about some bugs in the display, when the block moves to far to the left or right. It generates some flickering in the output. Maybe we can save some bytes to get the missing handlers into the 140 bytes!

Or did you found some errors in the logic?

tsaniel commented Jan 27, 2012

No, temporarily just found the bug that you just mentioned.

maettig commented Jan 27, 2012

I'm looking at the code and ... just wow!

Edit: Save 1 byte?

function(a,b,c,d,e){return d+=c,e=a|b<<d,d<0|a&b<<d&&(a=e=parseInt((a|b<<c).toString(32).replace(/v/,""),32),b=new Date%2?1:3),[a,b,d,e]}

tsaniel commented Jan 27, 2012

@maettig: It seems you forget the d in [a,b,d,e].


aemkei commented Jan 27, 2012

Right, we need to reset d to 32 when a collision was detected.
But the reordered version and new Date&2|1 will save 3 bytes:

function(a,b,c,d,e){d+=c,e=a|b<<d,d<0|a&b<<d&&(a=e=parseInt((a|b<<c).toString(d=32).replace(/v/,""),d),b=new Date&2|1);return[a,b,d,e]}

I have not delved into the logic, for which I apologize in advance.
parseInt can not be replaced by +?

@Evghenusi It could normally, but it's being parsed in base 32. ""+x only works for base 10 numbers.


tsaniel commented Jan 28, 2012

Updated: Save 7 bytes by using ?: instead of &&() and reusing variable c:
function(a,b,c,d){d+=c;c=d<0|a&b<<d?a=parseInt((a|b<<c).toString(d=32,b=new Date&2|1).replace('v',''),d):a|b<<d;return[a,b,d,c]}

tsaniel commented Jan 28, 2012

Save 11 bytes by reordering variables:
function(a,b,c,d){d+=c;return[d<0|a&b<<d?a=parseInt((a|b<<c).toString(d=32,b=new Date&2|1).replace('v',''),d):a|b<<d,a,b,d]}


aemkei commented Jan 28, 2012

Nice! So it's down to 128 (2^7) bytes. (Edit: 124 now!) I didn't see the last comment.

tsaniel commented Jan 28, 2012

So it's 1<<7-1<<2 bytes.


aemkei commented Jan 28, 2012

How about using the 16 left bytes to fix the wrapping issue when moving to far left / right?
Or move the initial board/block state into the core function?

tsaniel commented Jan 29, 2012

I would like to see both of them even if exceed 140 bytes. (we can shave the bytes off then)

plaes commented Feb 15, 2012

Just a little inspiration:


aemkei commented Feb 15, 2012

@plaes: Have you seen the version of Snake?

plaes commented Feb 15, 2012

@aemkei I was hinting that it would be cool to see a data-uri version of this snippet..

tsaniel commented Feb 15, 2012

@plaes: What about make it an 140bytes entry? (just the logic part fitted in 140 bytes, as "Tweetris")


ghost commented Feb 15, 2012

Excellent work!

Awesome code mate. Congratulations!

kendhia commented Feb 18, 2012

Awsome code. you made javascript more beautifull with this game !

Your licensing scheme is too restrictive.

Oh Wow wow wow wow wow!!!!! I am shocked, amazed, and laughing my head off!

And then I saw the licensing scheme! I am highly offended by the licensing scheme for it is entirely too restrictive! :D :D Why don't you loosen it up and allow me to rip it off and claim it as my own???

<3 <3 <3 <3 <3 love everything! thanks! inspires me to pursue JavaScript!


xmxkkk commented Feb 21, 2012

very awesome


I found you a bug if you keep holding the key to the left, it crashes, probably because the bits go off top. But other then that silly thing (The fact that I love breaking stuff) I have mad respect for doing it in 140 chars.

amazing work.

Nushooz commented Feb 21, 2012

Hey you left out the control and display code. This game is like 900 bytes working. You're a phony! Hey everybody, this guy is a great big phony!

From the license:

I just wanna fuck.

iznax commented Feb 23, 2012

I made a version with a larger play field and no edge wrap-around problems, but I can't quite get it down to 140 characters.

HAHA, so cute,

iznax commented Feb 27, 2012

here's my full version of Tetris with rotating pieces, the core function is 255 characters.

function(p,r,t,g,z){var k,d=z[0];z=((r+z[1])&15)-r;for(k=4;k--;)if(g[p+d+t[r+z+k]]){if(d>1){for(k=4;k--;)g[p+t[r+k]]=1;for(k=0;k<N*Y;k+=Y){for(d=2;d<Y;)d=g[k+d]?d+1:F;if(d<F)for(d=k;--d;)g[d+Y]=g[d];}p=W/2;t=T[new Date%7]}d=z=0;break}return[p+d,r+z,t,g]}

WYH2O commented Aug 29, 2013

wow .It's good.

Can you guys please send me examples of small games like this, I want to create collection of links. Thanks.

this 140bytes website... maybe you should remove the link ;]

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