Codex CLI on FreeGameStore

Build a free game using Codex CLI. The agent reads the platform's SKILLS.md and knows the brand rules, the CLI, and the deploy flow before it writes a line of code.

Before you start: install Node 22+ and the FreeGameStore CLI.

npm i -g @freegamestore/cli fgs login

Set up Codex

Install Codex
npm i -g @openai/codex

Or follow the latest install instructions at github.com/openai/codex.
Scaffold the game
fgs init my-game --template canvas cd my-game
Add platform context to AGENTS.md
Codex reads AGENTS.md at the project root the same way Claude reads CLAUDE.md:

cat > AGENTS.md <<'EOF' # Platform: FreeGameStore Read https://freegamestore.online/skills.md for the full platform guide. Constraints when editing this repo: - Manrope + Fraunces fonts only (no custom display fonts). - Use brand CSS tokens via var(--accent) etc. - Zero tracking SDKs. - Use the Shell component for layout. - Push to main = deploy. EOF
Start Codex
codex

Prompt the build

Build a markdown notes game: list of notes in the sidebar, full markdown editor in the main pane, live preview tab. Save in localStorage. Support import/export of a JSON backup.

Add a search box to my notes game that fuzzy-matches across title and content. Highlight matches in the preview.

Iterate

Run the dev server
cd my-game && pnpm install && pnpm dev

The agent will tell you which file it edited; refresh the browser to see the change.
Run compliance checks
fgs check

Catches missing brand fonts, tracking SDKs, oversized bundles, and missing PWA manifest before publish.
Publish
fgs publish --store games

Provisions github.com/freegamestore-online/my-game, the Cloudflare Pages project, the DNS record, custom subdomain at my-game.freegamestore.online, and the storefront entry — atomically.
Push your code
git push upstream main

Auto-deploys via Cloudflare Pages in ~30 seconds. Future commits to main deploy automatically.

What the AI knows (and doesn't ask you for)

Once SKILLS.md is loaded, the agent will:

Use the platform's CSS tokens (--accent, --ink, --paper, …) — never redefine them.
Use Manrope (body) + Fraunces (display) — never custom display fonts.
Refuse to add Google Analytics, Plausible, Mixpanel, or any tracker.
Use localStorage for persistence (or @freegamestore/games KV for connected games).
Push to main for deploy. Never wrangler pages deploy manually.
Never ask you for Cloudflare or GitHub tokens.

The compliance suite (fgs check) enforces all of the above on every push, so even if the AI slips, the platform catches it.

Get the source

The CLI, SDK, and compliance package live at https://github.com/freegamestore-online/platform. Reading the source is allowed — and often illuminating when you're trying to coax a difficult prompt.

Tips for Codex specifically

The /approval mode is good when you want to review every shell command Codex wants to run.
Codex auto-stages edits as a git diff — review with git diff before committing.
Pair with --model gpt-5 for the best reasoning on the platform's TypeScript + React idioms.