LambdaLabsHQ

Unity Repl — AI skill for Claude Code

AI community

Direct C# evaluator for the Unity Editor, enabling AI agents to automate workflows, build games, and verify behavior through executable C#.

How to install Unity Repl

This entry records only its repository, not the path inside it, so there is no exact command to give. Open LambdaLabsHQ/unity-repl and copy the folder into ~/.claude/skills/, or the file into ~/.claude/agents/.

What Unity Repl does

Direct C# evaluator for the Unity Editor, enabling AI agents to automate workflows, build games, and verify behavior through executable C#.

Alternatives in AI

Cwc Long Running Agents — Claude Code's built-in /goal command gives you a generator/evaluator loop out of the box: set a completion con 668 ★
Claude Hub — by Claude Did This - A webhook service that connects Claude Code to GitHub repositories, enabling AI-powered c 393 ★
Glade MCP — Connect any MCP-compatible AI client (Claude Code, Cursor, Windsurf) to Unity or Godot 201 ★

README

Unity REPL: The most powerful AI interface for Unity

[![License: AGPL-3.0](https://img.shields.io/badge/License-AGPL--3.0-blue.svg)](https://github.com/LambdaLabsHQ/unity-repl/blob/master/LICENSE)

Any sufficiently complicated C or Fortran program contains an ad hoc, informally-specified, bug-ridden, slow implementation of half of Common Lisp.

— *Greenspun's Tenth Rule*

An interpreter that evaluates an AI's output as code is superior to any form of tool-calling infrastructure, including MCP and CLI.

MCP servers and CLI wrappers are ad hoc interpreters slowly reconstructing what a REPL already is. **Unity REPL** skips the middleman: it grants AI agents direct, evaluative access to the Unity Main Thread through raw C# — no schemas, no wrappers, no human-curated endpoints. Token becomes language, language becomes execution, execution becomes the universal tool.

The agent executes a REPL script it previously discovered and crystallized from an earlier agent exploration session — which also used Unity REPL — with no pre-registered MCP tools and no hardcoded wrappers. Exploration turns into reusable automation.

Getting Started

Open your coding agent inside a Unity project, then paste the following prompt to install Unity REPL:

Add `"com.lambda-labs.unity-repl": "https://github.com/LambdaLabsHQ/unity-repl.git"` to the `dependencies` in `Packages/manifest.json`.

Then register the Unity REPL skill: try running `npx skills add ./Packages/com.lambda-labs.unity-repl`.

If that fails (e.g. Node.js is not installed), the skill definition is at `./Packages/com.lambda-labs.unity-repl/.agents/skills/unity-repl/SKILL.md` — use your agent runtime's skill installer to register it.

Finally, verify the REPL server is working by evaluating `Application.unityVersion` through the skill.

For step-by-step manual i