What Is LittleJS and How Can You Join Its Game Jams?

Updated

LittleJS is an open-source JavaScript game engine created by Frank Force, the developer behind frankforce.com (Killed By A Pixel). It's a lightweight engine for building browser-based games, and it has an annual game jam where developers build and submit games made with it. If you want to get involved, the practical path is: learn the engine, watch for the next jam announcement on frankforce.com, and submit a game before the deadline.

What LittleJS Is

Based on the site's own description, LittleJS is an open-source JavaScript game engine that Frank Force first released about four years ago. The engine has grown a following on GitHub, where it was approaching 4k stars at the time of the LittleJS Jam 2025 writeup.

The engine's appeal, judging by how Frank Force uses it himself, is small size and fast iteration. He builds tiny, constraint-driven games with it — for example, his JS1024 entry Skydreams squeezed a 3D endless racer into 1 KB of JavaScript, and his JS13K 2026 entry set fit four separate games into 13 KB zips each. That same "small but complete" philosophy is what the engine is built around.

The LittleJS Game Jam

The LittleJS Game Jam is an annual event for games made with the engine. The second one, LittleJS Jam 2025, was held the month before the site's post about it.

Detail LittleJS Jam 2025
Edition 2nd annual
Participants 160
Games submitted 19
Engine LittleJS (open source)

The gap between 160 participants and 19 submissions is worth noting if you're thinking about joining: plenty of people sign up, but far fewer finish and ship something. Planning for a small, completable scope is the realistic way to end up in the submitted column.

How to Get Involved

  1. Get the engine. LittleJS is open source and hosted on GitHub, where you can find the code and follow its development.
  2. Build something small first. The engine is designed for compact games, so a 1 KB or 13 KB style constraint is a good way to learn its API without over-scoping.
  3. Watch frankforce.com for the next jam. Jam announcements and results are posted there — the LittleJS Jam 2025 writeup is a recent example of how they're shared.
  4. Submit before the deadline. Past jams have drawn a mix of finished and unfinished entries, so the main thing separating participants from submitters is shipping.

Why It's Worth Trying

Frank Force has been entering size-constrained game competitions since at least 2019 (JS13K), and the engine he built for that kind of work is the same one the jam is centered on. If you're interested in tiny, browser-based games — or in a low-friction way to finish and release something — LittleJS and its jam are a direct route in. The engine is free and open source, and the jam is open to anyone who wants to build with it.