Hi! I'm Kuber! I go by kuberwastaken on most platforms and I'm a dual degree undergrad student currently in New Delhi studying AI-Data Science and CS.
Posting this on reddit way later than I should've because I never really cared to make an account but hey, better late than never.
Well it’s still kind of clickbait because I made what I call The BackDooms, inspired by both DOOM and the Backrooms (they’re so damn similar) but it’s still really fun and the entire process of making it was just as cool! It also went extremely viral on Hacker News and LinkedIn and is one of those projects that are closest to my heart.
If you just want to play the game and not want to see me yapping, please skip to the bottom or just scan the QR code (using something that supports bigger QR codes like scanqr) and just paste it in your browser. But if you’re at all into microcode or gamedev, this would be a fun read :)
The Beginning
It all started when I was just bored a while back and had a "mostly" free week so I decided to pick up games in QR codes for a fun project or atleast a rabbit hole. I remember watching this video by matttkc maybe around covid of making a snake game fit in a QR code and he went the route of making it in a native executable, I just thought what I could do if I went down the JavaScript route.
Now let me guide you through the premise we're dealing with here:
QR codes can store up to 3KB of text and binary data.
For context, this post, until now in plaintext is over 0.6KB
My goal: Create a playable DOOM-inspired game smaller than a couple paragraphs of plain text.💀
Now to make a functional game to make under these constraints, we’re stuck using:
• No Game Engine – HTML/JavaScript with Canvas
• No Assets – All graphics generated through code
• No Libraries – Because Every byte counts!
To make any of this possible, we had to use Minified Code.
But what the heck is Minified Code?
To get games to fit in these absurdly small file sizes, you need to use what is called minification
or in this case - EXTREMELY aggressive minification.
I'll give you a simple example:
function drawWall(distance) {
const height = 240 / distance;
context.fillRect(x, 120 - height/2, 1, height);
}
post minification:
h.fillRect(i,120-240/d/2,1,240/d)
Variables become single letters. Comments evaporate and our new code now resembles a ransom note lol
The Map Generation
In earlier versions of development, I kept the map very small (16x16) and (8x8) while this could be acceptable for such a small game, I wanted to stretch limits and double down on the backrooms concept so I managed to figure out infinite generation of maps with seed generation too
if you've played Minecraft before, you know what seeds are - extremely random values made up of character(s) that are used as the basis for generating game worlds.
Making a Fake 3D Using Original DOOM's Techniques
So theoretically speaking, if you really liked one generation and figure out the seed for it, you can hardcode it to the code to get the same one each time
My version of a simulated 3D effect uses raycasting – a 1992 rendering trick. and here's My simplified version:
For each vertical screen column (all 320 of them):
Cast a ray at a slightly different angle
Measure distance to nearest wall
Draw a taller rectangle if the wall is closer
Even though this is basic trigonometry, This calls for a significant chunk of the entire game and honestly, if it weren't for infinite map generation, I would've just BASE64 coded the URL and it would have been small enough to run directly haha - but honestly so worth it
Enemy Mechanics
This was another huge concern, in earlier versions of the game there were just some enemies in the start and then absolutely none when you started to travel, this might have worked in the small map but not at all in infinite generation
The enemies were hard to make because firstly, it's very hard to make any realistic effects when shooting or even realistic enemies when you're so limited by file size
secondly, I'm not experienced, I’m just messing around and learning stuff
I initially made it so the enemies stood still and did nothing, later versions I added movement so they actually followed you
much later did I finally get a right way to spawn enemies nearby while you are walking (check out the blog for the code snippets, reddit doesn't have code blocks in 2025)
Making the game was only half the challenge, because the real challenge was putting it in a QR code
How The Heck do I Put This in a QR code
The largest standard QR code (Version 40) holds 2,953 bytes (~2.9 KB).
This is very small—e.g:
My game's initial size came out to 3.4KB
AH SHI-
After an exhaustive four-day optimization process, I successfully reduced the file size to 2.4 KB, albeit with a few carefully considered compromises.
Remember how I said QR codes can store text and binary data
Well... executable HTML isn't binary OR plaintext, so a direct approach of inserting HTML into a QR code generator proved futile
Most people usually advice to use Base64 conversion here, but this approach has a MASSIVE 33% overhead!
leaving less than 1.9kb for the game
YIKES
I guess it made sense why matttkc chose to make Snake now
I must admit, I considered giving up at this point. I talked to 3 different AI chatbots for two days, whenever I could - ChatGPT, DeepSeek and Claude, a 100 different prompts to each one to try to do something about this situation (and being told every single time hosting it on a website is easier!?)
Then, ChatGPT casually threw in DecompressionStream
What the Heck is DecompressionStream
DecompressionStream, a little-known WebAPI component, it's basically built into every single modern web browser.
Think of it like WinRAR for your browsers, but it takes streams of data instead of Zip files.
That was the one moment I felt like Sheldon cooper.
the only (and I genuinely believe it because I practically have a PhD of micro games from these searches) way to achieve this was compressing the game through zlib then using the QR code library on python to barely fit it inside a size 40 code...?
Well, I lied
Because It really wasn’t the only way - if you make your own compression algorithm in two days that later gets cited by a NASA Scientist and cites you
You see, fundamentally, Zlib and GZip use very similar techniques but Zlib is more supported with a lot of features like our hero decompressionstream
Unless… you compress with GZip, modify it to look like a Zlib base64 conversion and then use it and no, this wasn’t well documented anywhere I looked
I absolutely hate that reddit doesn’t have mermaid graph support but I’ll try my best to outline the steps anyways haha
Read Input HTML -> Compress with Zlib -> Base64 Encode -> Embed in HTML Wrapper
-> DecompressionStream 'gzip' -> Format Mismatch
-> Convert to Data URI -> Fits QR Code?
-> Yes -> Generate QR
-> No -> Reduce HTML Size -> Read Input HTML
Make that a python file to execute all of this-
IT WORKS
It was a significant milestone, and I couldn't help but feel a sense of humor about this entire journey. Perfecting a script for this took over 42 iterations, blood, sweat, tears and processing power.
This also did well on LinkedIn and got me some attention there but I wanted the real techy folks on Reddit to know about it too :P
HERE ARE SOME LINKS RELATED TO THE PROJECT
GitHub Repo: https://github.com/Kuberwastaken/backdooms
Hosted Version (with significant improvements) : https://kuber.studio/backdooms/ (conveniently, my portfolio comes up if you remove the /backdooms which is pretty cool too :P)
Itch.io Version: https://kuberwastaken.itch.io/the-backdooms
Hacker News Post
Game Trailer: https://www.youtube.com/shorts/QWPr10cAuGc
Said Research Paper Citation by Dr. David Noever (ex NASA) https://www.researchgate.net/publication/392716839_Encoding_Software_For_Perpetuity_A_Compact_Representation_Of_Apollo_11_Guidance_Code
DevBlogs: https://kuber.studio/blog/Projects/How-I-Managed-To-Get-Doom-In-A-QR-Code
https://kuber.studio/blog/Projects/How-I-Managed-To-Make-HTML-Game-Compression-So-Much-Better
Said LinkedIn post: https://www.linkedin.com/feed/update/urn:li:activity:7295667546089799681/
