Independent guide based on upstream documentation reviewed October 10, 2026. Installation routes and tool capabilities below are documented by their authors; this site has not tested every agent or asset workflow.
Codex: check the upstream plugin route
The reviewed README lists two terminal commands for Codex: codex plugin marketplace add rehan-remade/universal-modder, followed by codex plugin add universal-modder@universal-modder. These are upstream installation instructions, not commands this website has run on your behalf. Check your installed CLI’s help if a command is unavailable.
The clone also contains .agents/skills and .codex/config.toml. Ask the agent to identify the instructions and available tools it can actually read. Finding a configuration file is not proof that every external service is authenticated or usable.
Gemini CLI: install and inspect the extension
The upstream route is gemini extensions install https://github.com/rehan-remade/universal-modder. Gemini’s official documentation describes extensions as packages that can include prompts, MCP servers and skills. After installation, use gemini extensions list or the interactive extension list to review its status.
If the extension is listed but a tool fails, separate agent authentication, extension loading and the tool’s own requirements. Keep the exact error and installed versions. Reinstalling repeatedly will not fix an absent Python executable or an unavailable asset server.
OpenCode and Cursor: inspect the workspace configuration
For OpenCode, the README says to clone the repository and run opencode inside it. Its opencode.json points to the skills and fal MCP server. OpenCode’s official configuration guide describes project-level configuration, so opening a different working directory can change which settings apply.
For Cursor, the README lists the Marketplace or cloning the repository, where agent instructions and .cursor/mcp.json provide context and MCP setup. Review what the workspace enables before allowing tool calls. This guide groups the integrations to help you choose a setup path; it does not claim equal performance or that we tested each agent.
Run the same small acceptance check whichever agent you choose
- Confirm the agent recognizes the relevant modding instructions and can explain the selected game’s loader route.
- Check that um --help works in the terminal used by the agent, and record the Python and game-tool versions.
- Leave optional paid asset calls out of the first milestone. An unavailable fal key should not block a plan using placeholder art.
- Require a plan, one buildable change, a real local test and a rollback path. Keep other game versions pending verification.
Choose for your workflow, then review the evidence
An editor-based workflow may suit reviewing files side by side; a terminal workflow may suit an existing command-line project. Your familiarity matters more than a promise that one agent can mod everything. Provider usage and subscriptions remain separate costs. For Claude Code’s dedicated installation walkthrough, use our setup page; the first-use tutorial applies after any chosen integration is ready.
A starter prompt for your agent
Identify my chosen agent and the Universal Modder installation route documented upstream. Check installed instructions, um CLI access and optional MCP tools separately. Do not assume a missing asset key blocks placeholder work. Read the relevant game note, then propose one small change with build, local test and rollback checks. List unresolved setup issues before editing game files.