Unity.Gamedev.Kit

An OpenCode plugin that sets a Unity project up for agent-driven game development:

• Connects the AnkleBreaker Unity MCP server (unity_* tools) and Context7 docs, with no mcp block to write.
• Adds a unity-openspec-workflow skill and loads the skill packs that npx skills add installs into .agents/skills, which OpenCode V2 does not scan on its own.
• Lets the built-in plan agent write OpenSpec planning files (openspec/, docs/, AGENTS.md) while every other edit stays blocked in plan mode.
• Blocks edits to Unity's generated folders (Library/, Temp/, Obj/, Logs/, UserSettings/, MemoryCaptures/) and to credential files (.env*, *.keystore, *.pem, id_rsa* ...).
• Adds the /unity-bootstrap, /unity-connect, /spec-feature and /unity-verify commands and the gamedev_bootstrap_stack and gamedev_status tools.
• Adds short Unity/OpenSpec rules to the agent's system prompt.

It targets the OpenCode V2 plugin API (@opencode/plugin) and also ships a smaller OpenCode 1.x entrypoint (1.18.29 or newer).

Install

OpenCode V2

opencode plugin add @heretek-ai/unity.gamedev.kit

or add it to the project's opencode.jsonc:

{
  "$schema": "https://opencode.ai/config.json",
  "plugins": ["@heretek-ai/unity.gamedev.kit"]
}

OpenCode 1.x (1.18.29+): add "plugin": ["@heretek-ai/unity.gamedev.kit"] to opencode.json.

Unity side. The unity_* tools talk to a bridge that runs inside the Unity Editor. In Unity, open Window > Package Manager > + > Add package from git URL and add:

https://github.com/AnkleBreaker-Studio/unity-mcp-plugin.git

First run

1. Open the Unity project folder in OpenCode.
2. Run /unity-bootstrap. OpenCode asks before it runs, because the bootstrap does global npm installs. It installs:
   • six skill packs with npx skills add <pack> --agent opencode: gamedev-skills/awesome-gamedev-agent-skills, vercel-labs/skills (find-skills), unity-technologies/industry-ai-workflows, unity-technologies/unity-agent-plugin, unity-technologies/skills, mattpocock/skills
   • the OpenSpec CLI (npm i -g @fission-ai/openspec), then openspec init --tools opencode if openspec/ is missing
   • @aerovato/operator-helper, then operator-helper install opencode-v2
3. Open the project in the Unity Editor, then run /unity-connect.

The same bootstrap runs outside OpenCode with npx @heretek-ai/unity.gamedev.kit (flags: --no-skills, --no-openspec, --no-operator-helper).

Commands and tools

Name	What it does
/unity-bootstrap	Runs gamedev_bootstrap_stack, then gamedev_status, and reports what is missing.
/unity-connect	Finds running editors with unity_list_instances, selects one, and reports editor state and compile errors.
/spec-feature <idea>	Interviews you with grill-me/write-a-prd, then writes an OpenSpec change.
/unity-verify	Checks the active OpenSpec change against the Unity console and EditMode/PlayMode tests.
gamedev_bootstrap_stack	The installer above, as a tool the agent can call. Asks permission first.
gamedev_status	Reports Unity projects found, whether the Unity MCP package is in Packages/manifest.json, and OpenSpec/skill folders.

Options

Pass options with the object form of the plugin entry:

{
  "plugins": [
    {
      "package": "@heretek-ai/unity.gamedev.kit",
      "options": { "unityHubPath": "C:/Program Files/Unity Hub/Unity Hub.exe", "installOperatorHelper": false }
    }
  ]
}

Option	Default	Effect
enableUnityMcp	true	Register the unity MCP server (skipped if you already define one).
unityMcpCommand	["npx","-y","anklebreaker-unity-mcp@latest"]	Command that starts the Unity MCP server.
unityHubPath	unset	Passed to the server as UNITY_HUB_PATH for Unity Hub tools.
enableContext7	true	Register the context7 MCP server (skipped if you already define one).
skillDirectories	[".agents/skills","~/.agents/skills"]	Extra skill folders to load.
planWritablePaths	["openspec/*","docs/*","AGENTS.md"]	Paths the plan agent may edit.
protectGeneratedFiles	true	Block edits to Unity generated folders and credential files.
injectSystemPrompt	true	Add the Unity/OpenSpec rules to the system prompt.
installOperatorHelper	true	Include Operator Helper in the bootstrap.
autoBootstrapOnLoad	false	Run the bootstrap once per project when the plugin loads, without asking.

OpenCode 1.x differences

The 1.x entrypoint registers the MCP servers, the four commands, the system prompt rules and the edit guard. It has no gamedev_* tools and no plan-agent change; there /unity-bootstrap runs npx @heretek-ai/unity.gamedev.kit through the shell tool.

Develop

npm install
npm test        # builds to dist/ and runs the tests

server.js at the package root lets OpenCode load a local checkout ("plugins": ["/path/to/unity.gamedev.kit"]); run npm run build first.

Publish

Releases publish from GitHub Actions with npm trusted publishing (OIDC), so no npm token is stored in the repository. .github/workflows/publish.yml runs when a GitHub release is published.

One-time setup:

1. The first version has to exist on npm before a trusted publisher can be attached. From a clean checkout: npm login, then npm publish (it runs the typecheck and tests first). Your npm account needs publish rights in the heretek-ai organization.
2. On npmjs.com, open the package's Settings > Trusted publishing, choose GitHub Actions, and enter organization Heretek-AI, repository unity.gamedev.kit, workflow publish.yml.
3. Optionally, in the same settings page, set Publishing access to require 2FA and disallow tokens, so only the workflow can publish.

Each release after that: bump version in package.json, merge, then publish a GitHub release tagged v<version>.