---
title: "Colyseus alternative for multiplayer games made with an AI"
description: "This page is written by the KUMODeck team. It compares KUMODeck with Colyseus for adding online multiplayer to a game you make with an AI, using facts from Colyseus' official pages."
url: "/docs/compare/colyseus/"
lang: en
index: "/llms.txt"
---
# Colyseus alternative for multiplayer games made with an AI

This page is written by the KUMODeck team. It compares KUMODeck with Colyseus for adding online multiplayer to a game you make with an AI, using facts from Colyseus' official pages.

Colyseus is an open-source game server framework for Node.js: you write the server's rooms and state in TypeScript, then run that server yourself or on Colyseus Cloud. With KUMODeck, there is no game server to write or run. You ask your AI, such as Claude Code, Codex or ChatGPT, to "make it playable online", and it adds KUMODeck's hosted rooms to the game you already have and puts it on a test link.

Both are reasonable choices. This page lists the facts so you can pick by how much of the server you want to own. Colyseus' facts come from its official pages, checked on 2026-11-05; its own pages are authoritative.

## At a glance

| | KUMODeck | Colyseus |
|---|---|---|
| What you build | the game only; rooms are a hosted part your AI turns on and calls from the browser ([Multiplayer rooms](/docs/guides/multiplayer/index.md)) | a Node.js server: rooms with lifecycle hooks (create, join, leave), state defined as a schema, and the client SDK in the game |
| Where the server runs | on KUMODeck; you do not need an account anywhere else ([Limits](/docs/limits/index.md)) | on your own servers (any Node.js host, with a process manager, a reverse proxy and HTTPS), or on Colyseus Cloud |
| Price | no free tier: at cost from a prepaid balance, from the first request; a 4-player, 30-minute match is about 0.31 to 0.47 cents when every move is carried ([Play online together](/docs/guides/play-online/index.md)) | the framework is free and MIT-licensed; Colyseus Cloud starts at $15 a month, has no free tier, and is paid monthly up front, with unused time credited if you delete a server |
| Growing | no rooms to provision; usage is billed as it happens | Cloud has no CCU, DAU or MAU limits; to handle more load you upgrade the server's resources, as auto-scaling is not offered yet |
| Game logic on the server | rooms relay messages and keep shared state; rules that must be checked go in your own [Functions](/docs/guides/functions/index.md) | built for authoritative servers: your room code runs on the server and decides the state |
| Matchmaking and room codes | quick match, private rooms with a 6-letter code, a public lobby, host migration | `joinOrCreate`, filters by options, a lobby room, a queue room, private and unlisted rooms; codes and passwords as recipes |
| Reconnects | the SDK reconnects by itself and keeps the seat 20 seconds by default, also across a page reload | automatic reconnection since 0.17 and a reconnection token for reloads; you set how long the server holds the seat |
| Player sign-in and saves | guests first, then email or quick sign-in; saves per slot with a version ([Authentication](/docs/guides/auth/index.md), [Cloud saves](/docs/guides/saves/index.md)) | an auth module (in beta) with email and password, anonymous sign-in and OAuth; you bring the database and email sending, or use `@colyseus/database` for accounts and versioned saves |
| Engines | the JavaScript SDK in the browser; Unity and Godot web games call it through a browser plugin ([Unity games](/docs/guides/unity/index.md)); other clients speak the rooms' WebSocket protocol themselves ([REST API](/docs/reference/rest-api/index.md#multiplayer)) | SDKs for TypeScript, React, Unity, Godot, Defold, GameMaker, Construct 3, Haxe, C and more |

Sources for Colyseus, checked on 2026-11-05: [Colyseus framework](https://colyseus.io/framework/) (open source, MIT, rooms, matchmaking, engines, self-host or Cloud), [Colyseus pricing](https://colyseus.io/pricing/) (open source free, Cloud from $15 a month), [Colyseus Cloud](https://colyseus.io/cloud-managed-hosting/) (no free tier, no auto-scaling yet, 32 locations, no CCU/DAU/MAU limits, deploying from the CLI), [Cloud pricing and billing](https://docs.colyseus.io/cloud/pricing-billing) (monthly up front, credit for unused time), [Deployment](https://docs.colyseus.io/deployment) (self-hosting checklist), [Matchmaking](https://docs.colyseus.io/matchmaker), [Reconnection](https://docs.colyseus.io/room/reconnection), [Auth module](https://docs.colyseus.io/auth/module) and [Database](https://docs.colyseus.io/database). Prices and limits can change; Colyseus' pages are authoritative.

## Where KUMODeck is different

**You add rooms to the game you have.** A game made with an AI is usually a page with no server. You ask in the same place where it was made: "Make it playable online." Your AI asks one short question about who plays, how fast the game is and whether cheating matters, shows the price of each answer, and adds a **Play online** button with quick match or a 6-letter code ([Make a Claude Code game multiplayer](/docs/use-cases/claude-code-multiplayer/index.md)). There is no server project, no build step and no process to keep running. If your AI is not connected to KUMODeck yet, [Start here](/docs/start/index.md) shows the steps for each AI.

**The cheap ways come first.** Not every game needs a server in the middle. For people you know, the players' devices can connect directly, and the moves cost 0 cents; KUMODeck still handles matchmaking, the room code, the host and the connection setup. For strangers, every move is carried, so other players never see roughly where you live from your connection ([Play online together](/docs/guides/play-online/index.md)).

**The rest of the backend is in the same project.** Hosting with test versions and your press on **Publish**, sign-in that starts with guests, and saves that follow players to every device come from the same connection to your AI ([A backend for your vibe-coded game](/docs/use-cases/vibe-coding-backend/index.md)). Your AI never sees a secret key ([Deploy a game from Claude Code without API keys](/docs/use-cases/claude-code-no-api-keys/index.md)).

**When a game does need checks on the server**, your AI can write them in your own [Functions](/docs/guides/functions/index.md), with one live object per match. A 10-minute, 4-player match there is about $0.0055 ([Pricing](/docs/pricing/index.md)).

## When Colyseus fits better

- **Your game's rules must run on the server.** Colyseus rooms are authoritative: the server decides the state, and the clients send input. That suits competitive games, physics that everyone must agree on, and anything worth cheating for.
- **You build in a native engine.** Colyseus has SDKs for Unity, Godot, Defold, GameMaker, Construct 3, Haxe and C, so a desktop or mobile build connects directly.
- **You want to own the servers.** The framework is MIT-licensed and runs on any Node.js host, so you choose the provider, the region and the code that runs.
- **You want a fixed monthly price.** Colyseus Cloud is a subscription per server, from $15 a month, with no limit on players by count.
- **You pick the regions.** Colyseus Cloud has 32 locations, each with its own endpoint.
- **You already have a Colyseus server**, or a team that knows Node.js and wants full control of the netcode.

## What it cannot do, and conditions

- **Rooms do not run your game's rules.** They relay and synchronise. A competitive game is host-authoritative, or checks moves in Functions.
- **The SDK is JavaScript for the browser.** There is no C# or GDScript SDK: Unity and Godot web exports reach it through a browser plugin, and a native build would speak the rooms' WebSocket protocol itself.
- **There is no free tier.** What your game uses comes out of your prepaid balance at cost. If the balance reaches $0, the game pauses for its players until you top up ([Prepaid balance](/docs/pricing/index.md#prepaid-balance)).
- **A room keeps nothing after the last player leaves.** Scores and progress belong in cloud saves.
- **Your AI cannot publish to everyone.** It can make test versions; the public address always waits for your press on a KUMODeck page.

## Questions and answers

### Do I need to write server code for multiplayer?

No. The rooms are hosted by KUMODeck, and your AI adds the calls to your game. Only rules that must be checked on a server need code, in your own [Functions](/docs/guides/functions/index.md).

### Can my AI write a Colyseus server instead?

It can. Colyseus' docs are written for that too, with a text version of every page. Then you or your AI also deploy the server and keep it running, on your own host or on Colyseus Cloud.

### Can players reconnect after their connection drops?

Yes. The SDK reconnects by itself, and the seat is kept for 20 seconds by default, up to 1 hour per mode. After a page reload, the same tab gets back into its seat while it is kept.

### Can a Unity or Godot game use KUMODeck rooms?

Yes, as a web export. The rooms are JavaScript calls in the browser, so a Unity game reaches them through a `.jslib` plugin, the same way as any browser API ([Unity games](/docs/guides/unity/index.md)).

### Is there a monthly fee for a server?

No. There is no server to rent. What your game uses is taken from your prepaid balance at cost, so a quiet month costs little. [Pricing](/docs/pricing/index.md) has a worked example with 200 players online at peak.

### Can I start with KUMODeck and move to Colyseus later?

Yes. The game files your AI wrote are yours. Moving means writing a Colyseus server for the rules and asking your AI to swap the KUMODeck room calls for the Colyseus SDK.