How to Build a Game in Roblox Using AI + Thrixel

Before you start, you'll need Roblox Studio installed and a Roblox account.

1. Install Rojo with VS Code

1. Install Visual Studio Code (VS Code).
2. Install the Rojo - Roblox Studio Sync extension for VS Code.
3. In VS Code, go to File > Open Folder and open an empty folder for the game.
4. Press Ctrl + Shift + P (Cmd + Shift + P on Mac) to open the command palette. Type “Rojo” and select Rojo: Open Menu.
5. If the menu says Rojo is not installed, click Install Rojo now.
6. Click Install Roblox Studio Plugin. If Studio is open, restart it. Rojo should then appear in Studio’s Plugins tab.

2. Add the Build World skill

Sign in

Sign in to Thrixel before installing the skill. The command is the same for every agent and requires uv. If uv isn’t installed, run the command for your operating system in a terminal:

curl -LsSf https://astral.sh/uv/install.sh | sh

irm https://astral.sh/uv/install.ps1 | iex

Run the sign-in command below. When the browser page opens, click Approve to connect your Thrixel account.

uvx thrixel-mcp@latest login

Install Build World

Choose your coding agent below. Build World needs both the skill, which provides the instructions, and the Thrixel MCP server, which provides the tools for generating assets.

claude plugin marketplace add thrixel/build-world
claude plugin install thrixel@thrixel

codex plugin marketplace add thrixel/build-world
codex plugin add thrixel@thrixel

{
  "mcpServers": {
    "thrixel": {
      "type": "stdio",
      "command": "uvx",
      "args": ["thrixel-mcp@latest"]
    }
  }
}

git clone https://github.com/thrixel/build-world ~/.thrixel/build-world
mkdir -p ~/.cursor/skills
ln -s ~/.thrixel/build-world/skills/build-world ~/.cursor/skills/build-world

git clone https://github.com/thrixel/build-world "$HOME\.thrixel\build-world"
New-Item -ItemType Directory -Force "$HOME\.cursor\skills" | Out-Null
New-Item -ItemType Junction -Path "$HOME\.cursor\skills\build-world" -Target "$HOME\.thrixel\build-world\skills\build-world"

gemini mcp add -s user --trust thrixel uvx -- thrixel-mcp@latest
gemini skills install https://github.com/thrixel/build-world --path skills/build-world

The Build World setup guide also covers manual installs, updates, and existing installations.

3. Set up Roblox Studio

Enable Studio’s MCP server so the agent can run code in Studio and take screenshots of the game.

1. Open Roblox Studio and create a new Baseplate. This creates a place, the Roblox file that holds the game’s world.
2. Click the Assistant icon at the far top-right of the window.
3. In the Assistant panel, open … > Settings > Manage MCP Servers. Turn on Enable Studio as MCP server. A green indicator confirms it is running.

4. Create a Roblox API key

Rojo doesn’t sync 3D model files. The agent uses a Roblox API key to upload the models separately.

1. Go to your Creator Hub credentials page and click Create API Key.
2. Under Access Permissions, add the Assets API system. Choose your account as the owner and enable Read and Write.
3. Under Accepted IP Addresses, add 0.0.0.0/0 or turn off IP restrictions. If this field is left empty, uploads will be unable to complete.
4. Since this key allows access from any IP address, set a short expiration, such as 30 days.
5. Click Save and copy the key. It is only shown once.
6. Save the key in a file named roblox_api_key.txt in the game folder. Keep this file out of Git.

5. Run the server

Start the server from VS Code

1. In VS Code, open the command palette with Ctrl + Shift + P (Cmd + Shift + P on Mac). Type “Rojo” and select Rojo: Open Menu.
2. If the folder has no Rojo project, click Create one now. Rojo adds default.project.json and the game’s starter folders.
3. Under Projects in this workspace, click the project’s name next to the play icon.

A popup in the bottom-right of VS Code confirms that the server is listening at localhost on port 34872. To stop it, open the Rojo menu and click the project again. The play icon changes to a stop icon while the server is running.

Connect Roblox Studio to the server

1. Return to the Baseplate place in Roblox Studio.
2. Open the Plugins tab and click Rojo.
3. Leave the address as localhost and the port as 34872, unless the server reported a different port.
4. Click Connect.
5. Under “Sync changes for project”, review the changes Rojo will make to the place and click Accept.

The Rojo window now shows the project’s name, server address, and a Disconnect button. Studio is connected and ready to receive changes.

If Studio can’t connect, open http://localhost:34872/ in a browser. A Rojo status page confirms the server is running.

6. Build your game

Thrixel Cubes

Thrixel charges Cubes for generating 3D assets. The total depends on the operations used and the number of assets in the game. Some operations have a flat cost, while others are metered and charged after they run. Building a full game can also use a large share of a coding agent’s plan limits. Check your balance before starting a large build, and see Thrixel’s website for current rates.

Run Build World

1. Open the coding agent in the folder containing the Rojo project.
2. Start a message with the Build World command for your agent:

   Agent	Command
   Claude Code	/thrixel:build-world
   Codex	$build-world
   Cursor	/build-world
   Gemini CLI	/build-world

3. Describe the game after the command. Include “Roblox” so the skill uses the right engine.
4. Mention that Rojo is already running, including its port, so the agent doesn’t start a second server.

In Codex, type $build and choose build-world from the skill picker before adding the game description.

/thrixel:build-world build an obstacle course game in Roblox set on floating islands. Rojo and its Studio plugin are already set up, and Rojo is serving this folder on port 34872, so don't start another server.

Accept changes in Roblox Studio

The initial Rojo connection is the approval step. Once connected, Rojo syncs changes as soon as the agent saves them to disk.

• When connecting: Rojo lists the differences between the files and the place. Click Accept to apply them, or Abort to cancel the connection. If there are no differences, it connects without asking.
• While the agent works: New and edited scripts appear in Studio automatically. If Studio was closed or disconnected, click Connect again when the agent asks. The agent can’t reconnect Rojo itself.
• To inspect changes: Click the time of the last change in the Rojo window to open View changes. It lists the changes applied and flags any that failed. Rojo changes also appear in Studio’s undo history.

To review a batch before syncing, open Settings in the Rojo window and set Confirmation Behavior to Always. Click Disconnect, let the agent finish, then click Connect to review the changes together. This review happens when connecting. Changes saved during an active connection still sync automatically.

Two things need manual attention:

• Save the imports. Rojo syncs scripts and instances. The agent uploads 3D models separately and inserts them into ReplicatedStorage.Assets, so those models aren’t stored in the project files. Use File > Save in Studio to keep them.
• Edit synced scripts in the project files. Rojo’s two-way sync is off by default. Edits made to those scripts in Studio don’t reach the files and can be overwritten.

7. Publish your game

Use File > Publish to Roblox in Studio when the game is ready to share.