How to Install Universal Modder in Gemini CLI (2026)

Quick install

Run this command in your ordinary terminal:

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gemini extensions install https://github.com/rehan-remade/universal-modder

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Before you start

Install and authenticate Gemini CLI by following its setup documentation. Confirm that Git is available in the same environment. If your installation uses npm, its supported Node.js runtime must also be installed there.

Use the shared Universal Modder requirements for Python, the CLI and optional asset tools. Check your chosen Gemini authentication method and billing directly with its provider; installing this extension does not create model access.

Step-by-step install

Step 1: Inspect the environment

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git --version
gemini --version
gemini extensions --help

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On a Node-based installation, also check node --version and npm --version. On PowerShell, if a .ps1 launcher is blocked, inspect whether the installed gemini.cmd or npm.cmd launcher is available and use it with the same arguments. A blocked launcher and a missing Git executable are different failures.

Install skill

Run the quick-install command, review the repository source and permission request, then inspect the extension and skills:

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gemini extensions list
gemini skills list

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Look for the universal-modder extension and its mod-any-game skill. An empty list is a discovery failure even if the command exits normally. Check whether another user or workspace skill has the same name before assuming which source is active.

Step 3: Choose optional asset settings

The extension configures fal for generated assets. For a code-only start, add --skip-settings to the install command:

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gemini extensions install https://github.com/rehan-remade/universal-modder --skip-settings

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Use this as an alternative installation command, not as a second required installation. The flag does not skip permission review. After installation, gemini mcp disable fal can disable that connection; inspect the result and confirm its state in the new session.

Step 4: Start a fresh session

Open Gemini in your project and inspect:

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/extensions list
/skills list
/mcp list

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The extension should be enabled, its skill visible and fal either connected with your chosen setup or intentionally disabled. If your CLI version exposes different management commands, consult its help rather than treating an unknown-command error as a successful check.

Check CLI

In the same ordinary terminal:

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um --help
um --version

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Also ask the agent to report the result from its tool shell. If it cannot find the command, use the standalone CLI installation and PATH diagnosis. The Python package declares 0.2.0; record the version your install reports.

Your first prompt

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Use mod-any-game to investigate my game installation at [local path].
Find prior knowledge-base notes, the actual engine, loader and save folders.
Plan one small change and an in-game verification step.
Create MODDING_PLAN.md with backup and recovery instructions before edits.

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For a concrete scope, follow the Terraria workflow in the tutorial. The FAQ explains platform and cost limits.

Common errors in Gemini CLI

spawn git ENOENT: check Git and the current directory in the installing process's environment. Follow the Git diagnostic.
Extension installed, skill absent: inspect the actual lists and skill sources, then restart the session in the intended workspace.
um is not recognized: check the Python CLI installation independently of extension discovery.
Authentication or quota error: inspect the account and model setup. Reinstalling Universal Modder cannot repair a provider quota or billing problem.

Uninstall

Exit Gemini, then use the ordinary terminal:

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gemini extensions uninstall universal-modder
gemini extensions list

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Open a fresh session to verify that its extension-origin skill is gone. User or workspace skills from other sources may remain. A separately installed um has a separate uninstall.

Other agents

Compare Claude Code, Codex, Cursor, VS Code / Copilot and OpenCode. The installation overview keeps all six agents and the skills-only route together.

Frequently asked questions

Do I type the extension install command inside Gemini chat?

No. Run gemini extensions install in your ordinary terminal. The slash commands shown later are for inspecting a running Gemini session.

Does spawn git ENOENT mean the extension is incompatible?

It usually means Git could not be launched, or the requested working directory could not be used. Check both in the same environment before investigating other causes.

Can I disable fal and keep the skills?

Yes. fal is an optional asset connection. Check that it is disabled in the session, then continue with code, placeholder art or your own assets.