If you’ve got time August 13th – September 13th, challenge your game development skills in js13kGames—a game jam for HTML5 game developers.

Like most game jams, participants make games based on a secret theme announced at the start of the competition. Unlike most game jams, submissions are limited to just 13 kilobytes after minification and compression. That doesn’t sound too challenging until you realize that a JavaScript game engine like Phaser is 815kB minified, and the image below is 13kB.

13kB image of Hubot

If you’re thinking this constraint would stifle creativity and limit playability, you’re mistaken. Check out some examples below as js13kGames organizer Andrzej Mazur (@end3r) looks back over some attention-grabbing entries from previous years.


The premier event kicked off and challenged participants to create a game based on the theme Number 13. The winning entry was a mouse accuracy and agility game called SpacePi by @jackrugile that revolves around the defense of 13 bases.

SpacePi by @jackrugile

It was the first js13k entry I started playing and couldn’t stop. I spent half of the day sucked to the monitor by the awesome gameplay, beautiful visuals, and overall feel. I sent the link to my friends, and a few hours later they were still complaining they couldn’t stop playing!


This year’s theme was Bad Luck, and @jackrugile won for the second year in a row with Radius Raid—a space themed shoot ’em up where you blast away unrelenting enemies before they destroy you.

Radius Raid by @jackrugile

The amount of polish and attention to detail is still impressive, even after so many years have passed.


2014’s theme was The Elements: Earth, Water, Air, and Fire.

The competition was tough. Ultimately, @Siorki took first place with Pest Control: Weasels—an arcade puzzle game similar to Lemmings (but with a twist).

Pest Control : Weasels by @Siorki

The overall quality of the entries in 2014 went through the roof. I really enjoyed the mayhem and visual effects of Extreme Mini Massacre, and was impressed by AP11, which looked like a proper GTA1 inspired game one could made in 13 kilobytes.


The theme for 2015 was Reversed.

In Behind Asteroids—The Dark Side by @gre, you play a classic game of Asteroids, but don’t control the ship! @remvst placed twice in 2015—in fifth with Taxi Drift and fourth with It’s Raining… Boxes?!

Two games in the top 5 out of 160 entries is really impressive,” according to Andrzej.

Behind Asteroids - The Dark Side by @greweb

I was in love with the style of the main character of Captain Reverso, played RoboFlip, deeply enjoyed Road Blocks, and the winning entry Behind Asteroids showed other devs that you can actually use shaders within the limit and end up with incredible effects like a shadow of the player approaching the machine.


As the name of the top two entries from 2016 (Evil Glitch and Glitch Buster) might suggest, last year’s theme was Glitch. Even after the competition the developers (@agar3s and @remvst respectively) continued work on their entries and published the games on Steam.

Evil Glitch by @agar3s

Glitch Buster by @remvst

It’s great to see the ideas that were born during the compo end up as full-blown games widely available to the public. They’re both available as prizes this year so they can serve as an example of what can be achieved if you really believe in what you’re doing.


The theme for this year will be announced on August 13th. Be sure to check out the js13kGames website for more information and resources to help get started. You’ll find micro game engines and boilerplates, the latest minification tools, audio and video, tutorials, and more!