HTML5 and JavaScript Game Development Competition in just 13 kB

What is js13kGames?

Js13kGames is a JavaScript coding competition for HTML5 Game Developers. 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 2018. Theme for 2018 was: offline.

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.

WebXR category

Submission deadline:


Mozilla Microsoft GitHub
eBay Spartez Photon Engine
Workday Blur Game Distribution
Horizon Games


Jscrambler LoadView

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


Jimmy Joe McGurl

Jimmy Joe McGurl

Director of Gaming at BLUR, formerly ranked professional gamer (59th in North America) and top commentator for Super Smash Bros., CRT-loving Retro Gamer.

@ohjimmyjoe |

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. He is currently the Senior Developer Advocate for Mixed Reality at Mozilla. Josh believes in the power of technology thoughtfully applied, and the need for better human computer interfaces.

@joshmarinacci |

Pablo Farías Navarro

Pablo Farías Navarro

Game developer and founder of Zenva. Since 2012, Pablo has been teaching online how to create games, apps and websites to over 200,000 students through Zenva Academy, and created content for companies such as Amazon and Intel.

@ZenvaTweets |

Christof Wegmann

Christof Wegmann

Christof Wegmann is founder and CTO of Exit Games and develops the realtime, multiplayer, cross-platform product "Photon". Photon is used by more than 300,000 game developers - including companies like Square Enix, Ubisoft, Disney, Warner Bro, SEGA, Miniclip, Codemasters, Glu, Rilisoft or World Golf Tour. The high performance Photon Server and Photon Cloud allow cross-platform gaming between Mobile, PC, Console, Web, VR/AR and other popular devices.

@bertelmonster2k |

Spartez Team

Spartez Team

Maciej Szpyra, Michał Nykiel, Paweł Skierczyński and Victor Debone. Developers during the day, gamers during the night. At Spartez, our personal passion for games was big enough that we needed to bring more team members to the jury, and we are ready to play all the games coming from 2018 developers 🕹🕹🕹 with some expectations from multiplayer games.

@thisisspartez |

Larry Chupacabra

Larry Chupacabra

Youtuber ⁄ Graphic Designer who shares & reviews a variety of different games - everything from Indie Gems to AAA titles. A veteran of numerous game jams, he's featured & given feedback on entries in everything from the 7DFPS Jam to Ludum Dare 29.

@larrychupacabra |

Pedro Fortuna

Pedro Fortuna

Co-founder and owner of Jscrambler where he co-leads business development, and supervises all R&D and technical activities. Inventor and co-author of three patents in the Computer Security area. Holds a degree and a MSc in Computer Science. Speaker at several IT events, related with Security and JavaScript.

@pedrofortuna |

Winners (Overall)


3rd place Raven by Elliot Nelson


6th place ONOFF by Bran Dunino


7th place Exo by Jack Oatley & ai Doge


10th place Re-Wire by Jan Mankopf


12th place ISP by Michael Wolken-Möhlmann


13th place LOGOUT by

    41-50. Welcome to the cyberspace, The Matr13k, Hans Fixes the Internet,
    This game has a random title, Envelope, [Hoverla], JS13K Battlegrounds,
    Richy the squeaker boy, Bulletcraft, When my vpn goes offline (...)
    51-60. Earth that was, America Offline, Silent network, Gunturion, Bellwoods, I Must Call My Grandmother, Internet Quest, Loadshedding, Gib, You have to get off line
    61-70. Space Force, Disconnect Maze, Audio Dash, Disconnect,
    SPACECRAFT, Interplanetary Postal Service, Storm Surge,
    The Void is Online, Angry Cleaning Robot, Energy Drink
    71-80. Charged, Close To Me, The Mail, Sand, Avoid Being Hit, Super++ Section,
    Mulligan's Island, Key Sprinter 13k, Offweb, Geoquiz 2
    81-90. Can you hear me?, Certified Professional, SYSTEMS, Key Battle,
    Peaceful Forest Walk, Connect, Captain Katamov, Misconnected, Pipes Rush, Zurbo
    91-100. Pronto, Fiber Optic, Cable Maze, Ranger Down, Cable in forest, Wander,
    Castle Escape, Quest of Tod, The Analyser, Take the network offline!
    101-110. Network Offline, Watashi no shashin, Shutdown, Maps Off!,
    ArcherFire: Duet of Aces, Dinoffline, Rain Bow, Offlab, Bo the dog, Chicken on a Line
    111-120. Offline Dinosaur Game, data_center, Singularity, 1024 Moves,
    Ladies Man, Balance, Hotspot Lovers, Labi, B1ack0ut, CD2 Offline
    121-130. Zero Distraction, Stay Off the Line!, Storm Of The Chaos Bane, NetShark, THE CORE,
    Off The Lines, ICE-X, Welcome to Cyberspace, Cloudapocalypsis now, Alone in darkness
    131-140. They Follow, Astro Miners, WIRED, Starship Toggle, Together Again,
    Pipe Net, Offline Mobile Gear, Goblin Tower 13k, Planet: Offline, FKnight
    141-150. ProjectConnect, Cat Out!, DOWNLOAD!!!, Packet Thief, Robot Coder,
    Blasting Shrapnel, Escape! Room, Emoji Swap, DISCONN3!CTED, Fluffline

Winners - Mobile


6th place Envelope by Xem, O.zattoni & Nghia

    21-30. Ranger Down, Quest of Tod, Network Offline, Pronto, Shutdown,
    Chicken on a Line, Singularity, Ladies Man, Balance, Zero Distraction
    31-40. Storm Of The Chaos Bane, Off The Lines, ICE-X, Cloudapocalypsis Now,
    Offline Mobile Gear, Together Again, FKnight, Packet Thief, Robot Coder, Sushi Kitchen

Winners - Server

Winners - WebXR

    11-15. Whirled on the Spirit Spiral, Gear Of War, Man on Wire,
    Keep them OFF the LINE, Sword Art Offline

Community Awards winners

Voted among the developers themselves.

  • 1. UNDERRUN by Phoboslab - 71 points
  • 2. The Chroma Incident by Ryan Malm - 55 points
  • 3. Bellwoods by Matt DesLauriers - 45 points
  • 4. Everyone's Sky by Rémi Vansteelandt - 44 points
  • 5. ONOFF by Bran Dunino - 41 points
  • 6. JS13K Battlegrounds by Cody Ebberson - 40 points
  • 7. Re-Wire by Jan Mankopf - 39 points
  • 8. Envisionator by Donitz - 36 points
  • 9. Exo by Jack Oatley & ai Doge - 32 points
  • 10. Hans Fixes the Internet by Madmarcel - 31 points
  • 11. Hold On by Andrew James Adams - 26 points
  • 12. Systems Offline by David Stark - 24 points
  • 13. Konnekt by Monsterkodi - 23 points
  • 14. [Hoverla] by Viktor Uhryn - 20 points
  • 14. 1024 Moves by GregPeck - 20 points
  • 16. Geoquiz 2 by Xem & Nghia - 19 points
  • 17. Quest of Tod by SamirH - 18 points
  • 17. Wander by Razh - 18 points
  • 17. Bulletcraft by Kakus - 18 points
  • 20. Go OFFLINE by Bartaz - 17 points
  • 20. SPACECRAFT by Csaba Csecskedi - 17 points
  • 22. Off The Line by Bryan Perfetto - 16 points
  • 22. Robo Galactic Shooter by Ashish Bardhan - 16 points
  • 22. Gib by Attila Horváth - 16 points
  • 22. Offline Paradise by Sirxemic - 16 points
  • 26. Castle Escape by Stuart Lee - 15 points
  • 26. Planetfall by Cheng Chiao - 15 points
  • 26. The Matr13k by Agar3s - 15 points
  • 29. __OFF_THE_LINE__ by Jesús Olmos - 14 points
  • 29. Stay Off The Red Line by James - 14 points
  • 31-34. Emoji Swap, Enmeshed, Interplanetary Postal Service, They Follow - 13
  • 35-36. Raven, Zurbo - 11
  • 37. Keep-Alive - 10
  • 38-45. Anti_Virus, Cat Out!, Planet Figadore has gone OFFLINE, Planet-X, Ranger Down,
    Submersible Warship 2063, You Are Offline, You have to get off line - 9
  • 46-47. All Systems Offline, Connection Defender - 8
  • 48-58. ISP, Man on Wire, Offline Dinosaur Game, Sum It Up, Earth that was, Pronto, Convo IRL,
    Envelope, Gunturion (Shoot the purple buildings), Key Battle, Line of Fire - 7
  • 59-66. I Must Call My Grandmother, Twisty Polyhedra, Robot Coder, Storm Of The Chaos Bane, Service Provider,
    Audio Dash, Offweb, Enjoy The Sunshine (Get Offline!) - 6
  • 67-81. Call Center Mess, Dinoffline, DISCONN3!CTED, Keep them OFF the LINE, Richy the squeaker boy,
    Silent network, SpaceDucts!, This game has a random title, When my vpn goes (...), You were disconnected,
    Faraday Cage Rampage, ICE-X, Sushi Kitchen, Captain Katamov, LOGOUT - 5



9 × WebStorm license

Nine personal licenses for WebStorm JavaScript IDE created by JetBrains.


10 × PlayCanvas account

Ten 6-month PlayCanvas Personal accounts offering a cloud-hosted, collaborative platform for building games.


30 × GitHub account

Thirty paid GitHub plans - personal accounts with unlimited private repositories for twelve months.

1 × account

One account with Startup plan for 12 months.

Construct 3

3 × Construct 3 license

Three Personal licenses for one year each of Construct 3 game engine created by Scirra.


3 × CodePen Pro account

Three CodePen Pro Starter accounts with lots of cool features for 12 months.


5 × NodeBB hosting

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

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.


3 × Jscrambler license

Three Jscrambler Professional licenses for three months each.

Evil Glitch

10 × Evil Glitch game

Ten copies of Evil Glitch game by Agar3s available on Steam.


2 × Dotcom-Monitor

Two Dotcom-Monitor performance monitoring accounts.


There are four different categories, you can submit your game to any of them - it's up to you.
There's a special page for everything about the new WebXR category 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.

We will also have the famous Community Awards voted among all the participants.


Desktop category (overall)

Top 100 games

  • 1st place:, CodePen Pro, Kendo UI, Making Money with HTML5, Phaser Editor, js13k t-shirt + CD
  • 2nd-3rd places: CodePen Pro, Kendo UI, Making Money with HTML5, Phaser Editor, js13k t-shirt + CD
  • 4th-5th places: Kendo UI, Making Money with HTML5, Phaser Editor, js13k t-shirt + CD
  • 6th-13th places: Phaser Editor, js13k t-shirt + CD
  • 14th-100th places: js13k t-shirt + CD

Mobile category

Top 10 games

  • 1st-2nd places: Construct 3, WebStorm, Gamedev Mini-Degree, Gamedev Using Phaser 3, Pyxel Edit, Dotcom-Monitor
  • 3rd place: Construct 3, WebStorm, Gamedev Mini-Degree, Gamedev Using Phaser 3, Pyxel Edit
  • 4th place: WebStorm, Gamedev Mini-Degree, Gamedev Using Phaser 3, Pyxel Edit
  • 5th place: Gamedev Mini-Degree, Gamedev Using Phaser 3, Pyxel Edit
  • 6th-10th places: Gamedev Using Phaser 3, Pyxel Edit

Server category

Top 5 games

  • 1st-3rd places: Jscrambler, Fullstack Webdev Mini-Degree, NodeBB, AppDrag Cloud Backend ⁄ CMS Pro
  • 4th-5th places: Fullstack Webdev Mini-Degree, NodeBB, AppDrag Cloud Backend ⁄ CMS Pro

WebXR category

Top 15 games

  • 1st-3rd places: Oculus Go, WebStorm, PlayCanvas, cardboard, js13k t-shirt + CD
  • 4th-5th places: WebStorm, PlayCanvas, cardboard, js13k t-shirt + CD
  • 6th-10th places: PlayCanvas, cardboard, js13k t-shirt + CD
  • 11th-15th places: cardboard, js13k t-shirt + CD

Community Awards

Top 30 games (voted among developers themselves)

  • 1st-5th places: HTML5 Games: Novice to Ninja, CryPixels, Evil Glitch, Glitchbuster, GitHub
  • 6th-10th places: Evil Glitch, Glitchbuster, GitHub
  • 11th-30th places: GitHub


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 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). Your game should work offline (Desktop and Mobile categories) and all the game assets should fit in the package size limit (not counting WebXR's A-Frame and Babylon.js frameworks). 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 "offline". 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 2018

The competition starts at 13:00 CEST, 13th August 2018 and ends at 13:00 CEST, 13th September 2018. No submissions will be accepted after the end of the competition.


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.

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.

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. If we cannot play your game, 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, judging and announcing winners

The Community Awards voting among the participants will last for a week between September 13th and 20th, winners will be announced on September 21st. Judges will vote for the games during the three week period after the submission time ends: from September 13th till October 4th, winners will be announced on October 5th.

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.

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.

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 or post them in the dedicated topic at the HTML5GameDevs forums.


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.