HTML5 and JavaScript Game Development Competition in just 13 kB

What is js13kGames?

js13kGames is a JavaScript coding competition for HTML5 Game Developers running yearly since 2012. The fun part of the compo is the file size limit set to 13 kilobytes. The competition started at 13:00 CEST, 13th August and ended at 13:00 CEST, 13th September 2021. Theme for this year was SPACE.

Read GitHub's tips and tricks article, check the Resources for tools,
read the Blog, and subscribe to the Newsletter - good luck and have fun!

The competition is organized by Andrzej Mazur from Enclave Games.

Check out the js13kGames 2021 winners!

Latest blog post: Badlucky joins Arcadians

Platinum Partners

eBay Tech NEAR Protocol IPFS
Grant for the Web

Gold Partners

Facebook Gaming GitHub Poki Coil
Colyseus Flux Filecoin
CrazyGames GameSnacks
Appfire 4everland

Silver Partners

Enclave Games SmartDust Outplay Games Gamedev.js

Share the love for HTML5 games and support the js13kGames competition!
See the Contact section for more details on how to get in touch.


Michelle Mannering

Michelle Mannering

Michelle is a Developer Advocate in the realms of innovation and technology. Known as the “Hackathon Queen” 👑 you'll often find her on stage MC’ing or speaking on a range of topics from artificial intelligence, to business, community engagement, the future of work, and esports. With a background in both science and arts, Michelle has a passion for gaming and combines this with her experience in a range of industries. Michelle brings a unique insight into gaming and is a gaming journalist and Twitch Streamer too!

@MishManners |

Noël Meudec

Noël Meudec

Partner Engineer at Facebook since 2017, working mainly on the Instant Games platform. I am a movie and video game addict, secretly dreaming of becoming a movie director. I joined and co-organized quite a few game jams (Global Game Jam in Singapore in 2018, 2019 and 2020, etc.). I am always excited to see how talented developers manage to make gems from constraints.

Ahmed Khalifa

Ahmed Khalifa

A game-AI researcher that is interested in automated game design and procedural content generation and a game designer ⁄ developer since 2005 creating more than 40 games on various platforms.

@amidos2006 |

Dann Sullivan

Dann Sullivan

Dann is the Editor of Pocket Gamer, Managing Editor for 148Apps and AppSpy, as well as the founder & Editor in Chief of Big Boss Battle (B3). He believes that curation and feedback can create a better, more fluid industry.

@FBFDann |

Tom Greenaway

Tom Greenaway

Tom Greenaway is the gaming lead for Chrome and Web Developer Relations at Google. He's also a multi-award winning game designer having created Duet for Android and iOS which was downloaded nearly 20 million times worldwide.

@tcmg |

Paul Gadi

Paul Gadi

Paul is CTO / Co-Founder of OPGames, focused on helping game developers successfully create decentralized games. He also leads the KERNEL Gaming Guild, a fellowship of the most talented builders in Web 3. He loves exploring the intersection of new technologies with game design, and believes that decentralization and shared virtual economies will revolutionize how we play games.

@polats |

Dietrich Ayala

Dietrich Ayala

Dietrich leads developer onboarding and ecosystem support at Protocol Labs, growing adoption of their protocols through developer experience, browser integrations, and strategic collaborations. Before Protocol Labs, he spent over a decade at Mozilla building browsers, shipping a smartphone OS and running programs to scale devrel globally.

@dietrich |

Aliaksandr 'Sasha' Hudzilin

Aliaksandr 'Sasha' Hudzilin

Aliaksandr studied business at UC Berkeley, worked in investment banking under Frank Quattrone, and spent 4 years selling and marketing MuleSoft and MemSQL products.

@aliaksandrh |

Vlad Grichina

Vlad Grichina

Vlad started his career as a professional TopCoder competitor and worked on mobile apps since 2009. He founded a 15 person mobile dev company and worked 3 years at Google on the Play Store.

@vgrichina |

Pablo Farías Navarro

Pablo Farías Navarro

Certified game developer and Founder of ZENVA - the world's leading platform to learn game making, VR, data science and full-stack programming. Since 2012, Pablo has been developing professional-grade courses that have helped over 1 million people learn to code and make games.

@ZenvaTweets |

Fazri Zubair

Fazri Zubair

Fazri is a software engineer/entrepreneur with a decade of experience in system architecture, software development, live operations, and studio management. As the CTO of Lucid Sight he spearheads the technical operations for Colyseus Arena, a Cloud Hosting solution for the popular Open-Source JavaScript multiplayer game server Colyseus. In his carrer Fazri has focused on emerging technology development and has worked with top brands and companies including Mattel, DC's Justice League, Viacom, Samsung, Star Trek, CBS, MLB, Scopley, Deluxe, and WB.

@FazriZubair |

Nathan Lie

Nathan Lie

Nathan is a Software Engineer at Coil who considers himself a gamer first and an engineer second. He's been working with and on applications using Web Monetization for the past year, and is eager to see the intersections between Web Monetization and game design this year!

@feraltc |

Yuriy Dybskiy

Yuriy Dybskiy

Yuriy is a founder of Puma Browser – mobile browser focused on seamless payments and data privacy. Previously worked at Lyft, Facebook, Meteor, Cloudant and a few startups as Developer Advocate ⁄ Engineer. Grew up in 🇺🇦🇯🇵🇨🇦. Lives in SF now, enjoys tennis, moto rides, park walks and games.

@html5cat |

Raf Mertens

Raf Mertens

Raf founded CrazyGames in 2013. Since then it’s grown to over 17M monthly users worldwide. Hundreds of game developers have tapped into that userbase to cross-promote and gain exposure to their games. Developers like SEGA (Sonic), Ubisoft (Hungry Shark Arena), Blue Wizard (Shell Shockers), Blayze Games (Bullet Force), and a vast community of indie creators. Find out how you can join them.

@CrazyGamesCom |

Fernando Serrano Garcia

Fernando Serrano Garcia

Software Engineer at Apple, previously worked at the Mozilla Mixed Reality team. Web, computer graphics and game development enthusiast.

@fernandojsg |

Josh Marinacci

Josh Marinacci

For over 20 years Josh Marinacci has worked as developer advocate, UX designer, researcher, engineer, and Twitch streamer. He has worked at such storied companies as Palm, HP, Nokia, Sun, and Mozilla. Formerly of Mozilla Mixed Reality team, currently working on Autonomous Vehicle Visualization. Josh believes in the power of technology thoughtfully applied, and the need for better human computer interfaces.

@joshmarinacci |

Steven Yau

Steven Yau

An experienced games developer with over a decade’s worth of experience ranging from AAA console games, XR and F2P mobile games for some of the largest companies in the games industry. Currently working as an engineer at PlayCanvas.

@yaustar |

Joep van Duinen

Joep van Duinen

Joep leads the game developer operations team at Poki, the number #1 platform for play on web. Poki is on a mission to create the ultimate online playground: a place where players and game developers come together to play and create. They help a growing 300+ game developer community - including Kiloo (Subway Surfers), Hipster Whale (Crossy Road) and Colin Lane (Dunkers) to achieve success on web. Here's more information about how game developers can get their html5 games featured on Poki.

@joepvduinen |

Daniel Keller

Daniel Keller

Daniel Keller comes from the data/information sector, and pursues the use of blockchain to further protect personal medical, financial and personal data through encryption and decentralized identification. Dan got involved in the cryptocurrency space through World of Warcraft, by using Bitcoin to buy "gold". He now works as the Chief Strategy Officer and Co-Founder of Flux, and helps push for a decentralized world with disruptive technologies.

@dak_flux |

Tim Sulmone

Tim Sulmone

Tim Sulmone is blockchain veteran and life-long video game addict. Beginning his journey by running a Bitcoin node in 2011, to then moving onto contributing towards various cryptocurrency projects, Tim is no stranger to decentralized infrastructure. He now leverages his experience as the Sr. Business Developer for Flux, to help further ensure that our world has a decentralized network to host on.

@little_stache |

Victor Debone

Victor Debone

Victor is a software engineer passionate about design and the user experience. He thinks games are the ultimate user experience. Given that, they require feedback and early exposure, which is the best gift judges can provide to JS13kGames participants and what he's here to do!


Pawel Skierczynski

Pawel Skierczynski

Pawel has played countless computer and board games. His primary focus is game design. What makes the game project successful? How to create a real masterpiece? He is ready to play your games and share with you some valuable feedback.


Winners (Overall)

    21-30.Billionaire Space Golf, Galaxies, Running out of space, 3DC5S, Get Out Of My Personal Space, SOS, Tenacity, Cat Goric: Escape from the Warp Chamber, Space Kitty, Operation Cleanaholeic
    31-40. Keep Your Space!, SpacePinball, VÅiD, spacew, Space refuel service, Joe's space, Stick Skater, Spaceship Escort, 2D4X13K, Interplanetary Transport System
    41-50. Distant Friends, Absorbed, ScriptFox13k, Space Arcade, 13 A.D., Space Exploration (2021), Safe Space, Space block invaders, Nestling Fears, Two Ships Passing In The Night
    51-60. Space Cowboy, Stay Safe, Space Portal, METAGRAV, Space Worm, 2021: a Space Opera, Shadow of the Keening Star, spaceChad, Max Damage: Crisis Mode, Invasion from Jupiter in Space
    61-70. Rogue-Hoarder, Xiiivious, A.S.T.R.O., The Space Between Us, Kosminenvirtaus, Space Arena, Seating Space Planner, Join the cubes, Orbital Golfing, hit SPACE to BEGIN
    71-80. Warp Station 13K, HDD Liberator, FRONTIERS, Rescue Mission, A Space in the Sun, Orbit Jump, Blanks Detective, Space Station Ordeal, Fill The Space, Earth Invader
    81-90. Space Jump, Space4, Yet Another MOBA, Solar Storm, Starshmup, Solar Defence, Go Away, Space, Space-Gum, Star Exploder
    91-100. Space Wallaby, Spacebar Clicker, Star Jaws, SPACE Saver, Space Quiz Shooter, Charming Rainbow Rabbit, Temporal Rift, Blinker, No more Space in Space, One Punch 1000 Demons

Winners - Mobile

    11-20. Space refuel service, 2021: a Space Opera, Max Damage: Crisis Mode, A.S.T.R.O., Go Away,
    Humwin & Darbold, Far From Ground Control, Space War, space capture, Azetz
    21-30. Asteroids Extended, Space sweeper, ESCAPE (2021), Galaxies, Blanks Detective, Space4,
    Space Wallaby, I just wanna warp home, Sci-Fi Alchemy, HyperSpace
    31-40. Space Defense Engineer, Space Game, Space Bar Maker, Master of 13k Suns, Space Jelly,
    SpacePinball, Space Worm, FRONTIERS, Earth Invader, Space Jump
    41-50. Solar Defence, Function Space, Low Fat Lard, Crater Space, Cat Goric: Escape from the Warp Chamber,
    Distant Friends, A Space in the Sun, _INVADERS, Space Invaders, Darkest Derelict
    51-60. Space Menace, Keep white space!!, Ant Space, Orbiter, Wonder Wanderer 3, LOSSST - a Snake in Space,
    Stick Skater, Spaceship Escort, 2D4X13K, Absorbed
    61-70. Spacebar Clicker, Astronaut in Trouble, Jeff's Nightmare, SPACE: Playful Adventures of Cat Emojis,
    Shh-Psst! Aliens!!! (CE), Sillies From Space, brokenSpace, Floating, The Space Bar Salooneasy, Astroach
    71-80. Spaceship Wars 13k, Space Invasion Simulator, Billionaire Space Golf, No more Space in Space,
    in ASCENT, I Need My Space!, Space-Gum

Winners - Server


4th place Space4 by Jorge Rubiano

Winners - WebXR

Winners - Web Monetization

Winners - Decentralized

Super Special

Super Special is an appreciation of a given entry that was original,
unique and stood up from the others - handpicked by Andrzej Mazur.

  • 1. Q1K3 by Phoboslab

Q1K3 is being awarded for the impressive ability of squeezing a Quake tribute into a 13 kb zip.


js13kGames 2021 t-shirt

130 × js13k 2021 t-shirt

One hundred js13kGames 2021 t-shirts (plus fifteen in WebXR category and another fifteen in Decentralized one) shipped worldwide for free.


Coil membership

Coil membership plans for six months each for every participant.


4000 FLUX coins

A total of 4000 FLUX coins worth around $2000* from Flux for the Decentralized category.


10 × PlayCanvas account

Ten PlayCanvas Personal plans offering a cloud-hosted, collaborative platform for building games, for 12 months each.

Construct 3

2 × Construct 3 license

Two Personal licenses of Construct 3 game engine for 12 months each and two $50 asset store vouchers.


9 × WebStorm license

Nine personal licenses for WebStorm JavaScript IDE created by JetBrains.

Kendo UI

5 × Kendo UI license

Five licenses of Kendo UI for ASP.NET (MVC & Core), PHP and JSP with priority support from Telerik for 12 months each.


5 × NodeBB hosting

Five Hamlet hosting plans for 12 months each from the NodeBB team.


13 × GitHub account

Thirteen paid GitHub Pro plans - advanced tools for your private repositories for 12 months each.

Zenva Academy

4 × Zenva Academy account

Four coupons for the access to the entire catalog of courses on Zenva Academy.

Colyseus Arena

5 × Colyseus Arena plan

Five Colyseus Arena Launch Pad plans for 12 months each.


10 × SmartDust account

Ten SmartDust premium accounts (varying levels) in a public cloud for a year, plus 1000 free hours for every participant with the code "js13kgames".

1 × account

One account with Freelancer subscription for 12 months
for all team members.


5 × Coil swag

Five Coil surprise swag packages.


5 × Poki swag

Five Poki surprise swag packages.


The first three categories (Desktop, Mobile, and Server) are voted by participants themselves separately,
while Web Monetization, WebXR, and Decentralized category results will be judged by the experts.

Desktop category (overall)

Top 100 games

  • 1st place: Proto, Kendo UI, WebStorm, Phaser Editor, GitHub plan and t-shirt, Pyxel Edit, js13k t-shirt
  • 2nd-5th places: Kendo UI, WebStorm, Phaser Editor, GitHub plan and t-shirt, Pyxel Edit, js13k t-shirt
  • 6th-9th places: WebStorm, Phaser Editor, GitHub plan and t-shirt, Pyxel Edit, js13k t-shirt
  • 10th place: Phaser Editor, GitHub plan and t-shirt, Pyxel Edit, js13k t-shirt
  • 11th-13th places: GitHub plan and t-shirt, Pyxel Edit, js13k t-shirt
  • 14th-15th places: Pyxel Edit, js13k t-shirt
  • 16th-100th places: js13k t-shirt

Mobile category

Top 10 games

  • 1st-2nd places: Construct 3, SpriteStack, Poki swag, SmartDust
  • 3rd place: SpriteStack, Poki swag, SmartDust
  • 4th-5th places: Poki swag, SmartDust
  • 6th-10th places: SmartDust

Server category

Top 5 games

  • 1st-3rd places: CodePen, Colyseus, NodeBB
  • 4th-5th places: Colyseus, NodeBB

WebXR category

Top 15 games

  • 1st-4th places: Zenva Academy, PlayCanvas, js13k t-shirt
  • 5th-10th places: PlayCanvas, js13k t-shirt
  • 11th-15th places: js13k t-shirt

Web Monetization category

Top 10 games

  • 1st place: $600, Coil swag, Making Money with HTML5, Coil membership
  • 2nd place: $300, Coil swag, Making Money with HTML5, Coil membership
  • 3rd place: $150, Coil swag, Making Money with HTML5, Coil membership
  • 4th place: $75, Coil swag, Making Money with HTML5, Coil membership
  • 5th place: $50, Coil swag, Making Money with HTML5, Coil membership
  • 6th-10th places: $25, Coil membership
  • 11th-all places: Coil membership

Decentralized category

Top 15 games

  • Protocol Labs challenge:
    • 1st place: 32 FIL (~$2000)
    • 2nd place: 16 FIL (~$1000)
    • 3rd place: 8 FIL (~$500)
    • 4th place: 4 FIL (~$250)
    • 5th place: 3 FIL (~$200)
    • 6th-10th places: 2 FIL (~$150)
  • NEAR Protocol challenge:
    • 1st place: 640 NEAR (~$2000)
    • 2nd place: 320 NEAR (~$1000)
    • 3rd place: 160 NEAR (~$500)
    • 4th place: 80 NEAR (~$250)
    • 5th place: 60 NEAR (~$200)
    • 6th-10th places: 40 NEAR (~$150)
  • Flux challenge:
    • 1st place: 4000 FLUX (~$500)
  • 1st-15th places: js13k t-shirt


There are six different categories, you can submit your game to any of them - it's up to you.
There are special pages for Web Monetization, WebXR, and Decentralized categories if you want to know more.

Desktop category


Full power of the hardware.

Mobile category


Handheld touch devices.

Server category


Node.js multiplayer.

WebXR category


Virtual reality.

Web Monetization category

Web Monetization

Earn money.

Decentralized category


Blockchain features.


Package size below 13 kB

All your code and game assets should be smaller than or equal to 13 kilobytes (that's exactly 13,312 bytes, because of 13 x 1024) when zipped. Your .zip package should contain index.html file in the top level folder structure (not a subfolder) and when unzipped should work in the browser. Don't overcomplicate building the zip package, it should unpack on any platform without problems. You can use tools that minify JavaScript source code.

Two sources - readable and compressed

The competition is focusing on the package size, but learning from others is also very important. Please provide two sources of your game - first one should be minified and zipped to fit in the 13 kB limit (sent via the form) and the second one should be in a readable form with descriptive variable names and comments (hosted on GitHub).

No external libraries or services

You can't use any libraries, images or data files hosted on server or services that provide any type of data - for example Google Fonts are not permitted (although you are allowed to ask users to live-load a web font to support some characters or emoji on devices that can't display them properly, but you have to make sure your game will work without them). Analytics and other stat-collecting scripts are also not allowed. All the game assets should fit in the package size limit (the A-Frame, Babylon.js, and Three.js frameworks are not counted towards the size limit, but you can use them only in the WebXR category). If you manage to shrink your favorite library below 13 kilobytes including the code itself, then you can use whatever you want, just remember about the 13 kB limit.

Main theme

Main theme for the competition is announced on August 13th. It's highly advised to follow it in your game, because the judges will pay attention to that, but you can freely interpret the theme and implement it however you feel would be the best.

Deadline - 13th September 2021

The competition starts at 13:00 CEST, 13th August 2021 and ends at 13:00 CEST, 13th September 2021. No submissions will be accepted after the end of the competition, although there may be exceptions to that.


You have to have the rights for every asset used in your game. Remember that the submitted games will be published and made available for everybody to see. On the other hand, you have the right to report any game publisher that will link to (or iframe) your entry on their portal without your permission.

New content only

Do not submit any old games or demos - you have a whole month to work on something new and fresh, this should be more than enough. Also, submitting Breakout or Flappy Bird clones taken out of a tutorial make no sense at all - try creating something at least a little bit more original. You can, however, use any available libraries and resources that are not yours, but you have the right to use them.

Errors and browser support

Your game must work and be playable in at least two browsers: latest Firefox and Chrome, but the more supported browsers, the better. There should be no errors - you can lose some points if your game is showing any errors in the console. Don't stress too much if there are any warnings, but if we cannot play your game, then it won't be accepted.


It doesn't matter if you're working alone or with your friends, just remember that the number of prizes is fixed, so you'll have to share your trophies with your teammates.

Sending submissions

There's a special form to submit your game. Please remember that you have to provide two sources (see the Rule #2 for details) - a link to a public repository on Github and a zipped package. Participants are allowed to submit more than one game in the competition, though sending the same game as independent submissions targeting different platforms (for example separate builds for desktop and mobile) is forbidden.

Accepting submissions

Submissions will be checked manually and published after positive verification. This may take up to a couple of days, so be patient if your game is not yet online. I claim the right to reject any submission without giving a reason, although I hope I don't have to. I also have the right to update the rules of the competition at any time.

Time frames for voting, giving feedback, and announcing winners

The voting among the participants will last for three weeks between September 14th and October 4th, winners will be announced on October 5th. Experts will give the games constructive feedback (one per game) during the same three week period - their comments will also be published on October 5th.

Save data ⁄ persistent memory

Remember to add prefix to your variables and create a namespace for your game when you save data to localStorage as all the games on the server share the same memory when played in the browser. Also, be sure to NOT use localStorage.clear() as it will wipe out all the data of all the other games. Manipulate the data you are sure is yours.

Code of conduct

All participants and judges at js13kGames are required to agree with the following code of conduct. Organizers will enforce this code throughout the online event. We are expecting cooperation from all participants to help ensuring a safe environment for everybody.

js13kGames is dedicated to providing a harassment-free competition experience for everyone, regardless of gender, sexual orientation, disability, physical appearance, body size, race, or religion. We do not tolerate harassment of competition participants in any form. Competition participants violating these rules may be sanctioned or expelled from the competition at the discretion of the competition organizers. TL;DR: Be excellent to each other. For more details see Berlin Code of Conduct.

Privacy policy

By entering your email address and sending a game through the submit form you agree to receive email communication about important events of the competition like announcing the winners or sending out the digital prizes, but also curated content from the partners about their tools, services, or job offers. I will never share your email with anyone though.

By submitting, you also grant the competition organizers the right to re-use the uploaded materials for advertisement of the competition in any form.

Frequently Asked Questions

Why exactly 13 kB?
Well... why not? :)
What's in it for you? Are you getting paid?
Nope, it's just my own idea and it's made for pure fun. I'd love to get a sponsorship though as I spent my own private money on the first edition to cover making t-shirts, shipping of the prizes worldwide, etc.
What does the "zipped" term exactly mean?
Sent package should be zipped with your usual system archiver, the only allowed extension is .zip. Let's keep it simple - it's a competition for coders and this should be your main focus, the code itself. Thanks to the zipped archive you will easily send your game and we will easily check the file size.
Can I use Flash?
No, you can code your game using only the open web technologies like JavaScript, HTML and CSS.
Can I use WebGL?
Yes, though it might be hard to fit it into 13 kilobytes if you plan on doing an FPS game.
Can I use CoffeeScript or TypeScript?
Yes, you can use it, but you can't submit it. Only JavaScript code will be accepted, so remember to have your compiled code within the 13 kB limit. This is to ensure that the submitted entries are an actual HTML page with scripts, not a binary.
Can I use WebAssembly and ⁄ or Rust?
Yes, after all those are web technologies, and can work well with JavaScript games if used properly.
Can I use compression through the self-extracting PNGs?
You can use it, but remember that the zip is as good, or even better in terms of compression than PNGs, so there's no point in doing so.
Do I have to register somewhere?
No, you just need to submit your game through a form when it's ready.
How many games can I submit?
As many as you want, there are no limitations.
More questions?
Send them in via email or social media.


If You have any questions or propositions please feel free to contact us via e-mail:
The other options include visiting our profiles on Twitter or Facebook,
or joining our Slack channel and sending us the private message.