Holyjam 2025 - Colyseus

Ratings

This jam is now over. It ran from 2025-12-08 03:00:00 to 2026-01-01 02:59:59. View results

Colyseus Holyjam 2025 is a cozy, low-pressure game jam where you create a multiplayer game using the power of Colyseus during the holidays.

Dates: 8–31 December 2025
Theme: Cozy Chaos

What is Colyseus?

Colyseus is an open-source backend framework for building multiplayer game servers. Features auto-sync, matchmaking, and scalability—works with your favorite engine!

Which Game Engine should I use?

Use whatever you're comfortable with! Colyseus is engine-agnostic and works with most game engine or frontend framework via its client SDKs.

We recommend you build targeting the web as it has the lowest friction to invite others to play - just share a URL and anyone can play from desktop or mobile, no installs needed.

See our Getting Started documentation.

Recommendations:

JavaScript/TypeScript:
- 2D
  - KAPLAY: JavaScript/TypeScript game library with small, clean and intuitive block-based API. (ex-Kaboom.js)
  - Phaser: One of the most popular and mature HTML5 game frameworks, feature-rich and well-documented.
  - Pixi.js: Lightweight 2D/3 WebGL rendering engine for interactive graphics and games
  - ...web frameworks such as React, Svelte, Vue, Angular, etc - or use straight DOM/JavaScript for lightweight custom engines.
- 3D
  - Three.js: The de-facto standard WebGL 3D library, lightweight, flexible and hugely popular
  - BabylonJS: Full-featured WebGL 3D engine with physics, PBR materials, scene editor and great tooling
- Game Engines:
  - PlayCanvas: Cloud-based WebGL 3D engine with real-time collaboration and excellent performance.
  - Construct 3: Powerful no-code 2D game engine using event sheets, exports instantly to HTML5.
  - Cocos Creator: Free open-source engine supporting both 2D and 3D, strong TypeScript support, popular in Asia.
Other (native engines with solid HTML5/Web export):
- Unity: Industry-leading engine with excellent 2D/3D tools and high-quality WebGL export (via Unity Web).
- Defold Engine: Lightweight, free, Lua-based game engine, very fast HTML5 export with small file sizes.
- Haxe: Cross-platform toolkit that compiles to highly optimized JavaScript (and many other targets)
- Godot Engine: Free open-source engine; HTML5 export supported via community-driven GDExtension SDK by gsioteam.

Worried you won't finish in time? 🫠

Dive in anyway! Holyjam 2025 is low-pressure and holiday-friendly—pick days that fit your schedule, keep the scope super minimal (just a 2-player multiplayer prototype), and watch the magic happen.

You'll learn tons about multiplayer dev, even if it's not "complete." Jams like this are the ultimate practice run!

The theme is just a suggestion to guide your game idea. (Not strictly required to follow)

We'll select up to 2 lucky winners and reach out to them! Each winner gets to pick one free gift — a T-shirt, hat, or mug — shipped straight to their door at no cost*!

(*Products are manufactured and shipped from the US, UK, EU, and Australia. If your shipping address is outside these regions, you may be required to pay customs duties and/or taxes upon receipt in your country, depending on the import laws and duty thresholds of your country)

✅ Must support real-time multiplayer for at least 2 players simultaneously.
✅ Must use Colyseus as the multiplayer server/framework.
✅ Be friendly and respectful to all participants.
✅ Teaming up/collaboration between participants is allowed and encouraged.
✅ Any game engine, library, or framework is permitted.
✅ Forking, reusing existing open-source code, or using free assets is completely fine.
✅ AI-generated content (code, art, music, etc.) is allowed and highly encouraged!
❌ No NSFW, offensive, or inappropriate content.
❌ No use of copyrighted material (music, art, code, etc.) without proper permission or license.

You’re free to host your server on any cloud provider you like
- DM the organizers in #gamejam on Discord channel to grab 1 month of FREE Colyseus Cloud hosting just for participating in the jam!
We strongly recommend deploying your game’s frontend to the web (e.g., itch.io, Vercel, Netlify, GitHub Pages, etc.) for maximum visibility and to make it easy for everyone to play instantly.
Sharing your source (whether open-source or just publicly viewable) is super welcome, but optional.

You retain full ownership of everything you create for Colyseus Holyjam 2025. Submitting to the jam does not transfer any rights or ownership to Colyseus or anyone else.

By submitting to Colyseus Holyjam 2025, you grant Colyseus the right to use, display, and feature your submission (including the game, itch.io page, artwork, screenshots, trailers, etc.) in Colyseus videos (e.g., on YouTube) and on official Colyseus social media channels (including but not limited to LinkedIn, X/Twitter, and Discord) without further permission or compensation.

We reserve the right to disqualify or remove any submission that violates the jam rules, contains inappropriate or harmful content, or for any other reason at the organizers’ sole discretion. We will make every effort to handle such cases fairly and transparently.