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Work in progress. These docs describe Spawnite at launch, and some parts are still being built.

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Your coding agent builds the game you imagine on Spawnite, a 3D game engine for the web with a platform that hosts the games made on it. From one prompt it sets up the tools, asks what game you want, and opens a first version in your browser for you to play.

What you need

Section titled “What you need”

You need the following on your computer:

  • Claude Code or Codex, signed in. Each is a paid service: Claude Code runs on a Claude subscription or Anthropic API credit, and Codex on a ChatGPT plan or OpenAI API credit. Spawnite itself charges nothing to build, publish or host a game.
  • Node 24.2 or later. Run node --version in a terminal to see yours.
  • A network that reaches npm, GitHub and assets.spawnite.com, where the shared models, sounds and textures load from.

Your agent runs the rest through npx @spawnite/cli, which fetches the Spawnite command line tool from npm, and downloads a copy of Chromium for its own playtests. It asks you before it runs each command, unless you have let it run commands on its own; a command it may not run, it asks you to run and paste the output. git is optional. With it, your game’s folder starts as a repository.

Make a game without writing code

Section titled “Make a game without writing code”

You write no code, but you do work with a coding agent, in a terminal, an editor or a desktop app, and the agent is a paid service. Paste this prompt into your agent, in any folder:

Let's build a game together on Spawnite. Before we talk about what to make, read this first: https://wiki.spawnite.com/learn/agent-checklist/

The agent follows the agent checklist, one step at a time:

  1. It runs the Spawnite command line tool once, which fetches the tool from npm. Your agent may ask you to approve the command first.
  2. It connects the Spawnite plugin to Claude Code or Codex, whichever you have. The plugin loads in your next session, or now if you type /reload-plugins in Claude Code; nothing waits for it, and your agent goes on in this one.
  3. It asks what game you want. Answer in a sentence in your own words, such as “a cat collects fish before the tide comes in”.
  4. It creates the game in the folder you started in when that is empty, and otherwise in a folder under it named for your game, installs its packages, and downloads Chromium once.
  5. It builds the game in six steps, with one question per step. Say “you decide” whenever you want it to choose. Each step ends with proof: a test for a rule, and a screenshot from a playtest for a look.
  6. When the six steps are done, it shows you a round, says what it proved and what it did not, and tells you how to play: the dev command your game’s AGENTS.md names, such as npm run dev, in the game’s folder, then the address it prints, such as http://localhost:5173/. A game with a room, one that friends join together, starts with spawnite play start instead.

Make your game says what each step asks.

Check that it worked

Section titled “Check that it worked”

Setup is done when the following are true:

  • The game plays in a tab of your browser, and the spawnite button at its top left opens the devtools, where you can pause the game, pick an entity and message your agent. Its editor works on the map while you build: you sculpt and paint the ground, set the sea, scatter trees and rocks, click models and simple shapes onto the map, and move, turn and scale them with handles, and Save writes them to the map’s file. Your agent writes everything else, including characters, items, rules and UI, and an inspector change to an entity lasts only once your agent writes it into the code.
  • Your agent answers “List the game templates.” with a list that names example, from its Spawnite tools or from npx @spawnite/cli list.

To start the game yourself in a later session, do the following in a terminal in your game’s folder:

  • For a game played alone, run the dev command your game’s AGENTS.md names, such as npm run dev, and open the address it prints. The command is spelled for the package manager that installed the game: npm, pnpm, yarn or bun.
  • For a game with a room, run spawnite play start through the same manager, such as npm exec spawnite play start, and open the address it prints. The dev command starts no room, so the game would play alone.

When a step fails

Section titled “When a step fails”

The following table lists the failures setup meets most often:

What you see What to do
The agent says Node is older than 24.2, or missing. Install Node 24 from nodejs.org, then tell the agent to go on.
The agent says it may not run a command. Run the command it shows in a terminal, in the folder it names, and paste what it printed back to the agent.
A tool fails with an error about $schema or another field. The plugin is older than the docs. Tell your agent to go on with the spawnite command, which does the same work; to update the plugin, run claude plugin update spawnite@spawnite, then type /reload-plugins in Claude Code.
A playtest fails while it downloads Chromium. Check the network, then run spawnite play install in your game’s folder.
Claude Code’s auto mode blocks a spawnite play command. Add the two rules in Let auto mode run spawnite.
A Codex tool call stops after 60 seconds. Add tool_timeout_sec = 600 under [mcp_servers.spawnite] in ~/.codex/config.toml.
The game in your browser looks wrong, or something happens oddly. Press F8 at that moment, then tell your agent what you saw. How your agent works on your game says what it does with the mark.

Troubleshooting lists the errors your agent may meet while it sets up and builds, with the fix for each, and Connect your agent has the plugin’s rows in full.

Where your game lives

Section titled “Where your game lives”

Your game lives only in a folder on your computer. The platform keeps the builds you publish, never the project the agent works in, so a lost laptop loses the game. When git is installed, the folder starts as a git repository, and the agent offers to back it up to a repository of your own, such as one on GitHub. Say yes, and the agent pushes your game there after each session’s work. Each push shows on the repository’s page, so you can see the last one there.

Share it with friends

Section titled “Share it with friends”

When you want friends to play, ask your agent to publish the game. It signs you in, creates the game on your account, then runs spawnite publish, which builds the game, uploads it, makes that version live and prints its link. The first publish is unlisted: only people with the link can open it, in a browser on a computer or a phone. In a game with a room, everyone with the link plays in one room until it is full, so to play with just your friends, publish unlisted and share the link. Once the game is public, a player can also open a private room for the people they invite. A game played alone runs on each player’s own page, so each plays a copy of their own. Building, publishing and hosting are free, and Spawnite keeps 30 percent of net sales: what players spend, less tax, refunds and the payment fee. Publishing says how a game goes on the store.

Next steps

Section titled “Next steps”

To take the setup by hand, read the following pages in order:

1. InstallCreate a game from npm, and run it.
2. Connect your agentAdd the Spawnite plugin to Claude Code or Codex, and check that it answers.
3. Make your gameStart a game from an idea or from the example.
Agent checklistThe same setup as numbered steps an agent follows on its own.

To see what your agent does while it builds, or to write the code yourself, read the following:

How your agent works on your gameHow your agent runs, looks at and fixes your game, with real commands.
A tour of the example gameA tour of the example game, file by file.
How a game fits togetherGames, scenes, worlds and entities, and what each one reads.