Real AI agent use cases, with sources and setup prompts

Make a GBA game with Codex and play it on a real Game Boy Advance

amrayupon created a cyberpunk-themed GBA game using Codex and the ModRetro Chromatic plugin and plays it on an original Game Boy Advance.

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Source

@amrayupon on X · 2026-10-19

Written in our own words. Credit to the original author. Link checked 2026-10-24.

What they did

amrayupon created a cyberpunk-themed GBA game using Codex and the ModRetro Chromatic plugin and plays it on an original Game Boy Advance.

Result (as claimed)

A homebrew cartridge-style game on real hardware.

Tools they used

CodexModRetro Chromatic plugin

Cost: Pricing depends on the tools you pick; check each official pricing page.

Set it up

  1. Write a one-page brief

    Describe the app in plain words: who it is for, the 3 core screens or actions, and what "done" looks like.

  2. Start the project with your agent

    Open Codex and paste the brief. Ask it to propose a stack and a file plan before writing code.

  3. Build one slice at a time

    Ship the smallest working flow first, run it, then add features one by one. Commit after each working step.

  4. Test it like a user

    Click through on desktop and phone. Ask the agent to add basic tests and fix anything that breaks.

  5. Check security and ship

    Keep keys in environment variables, check auth and database rules, then deploy and share the link.

Copy the full setup prompt

Paste into your agent and it will walk you through the setup, asking before anything that sends, posts or spends.

You are helping me set up this AI use case end to end in Claude Code.

Goal: Make a GBA game with Codex and play it on a real Game Boy Advance
What the original author did: amrayupon created a cyberpunk-themed GBA game using Codex and the ModRetro Chromatic plugin and plays it on an original Game Boy Advance.
Reported result (as claimed by the author): A homebrew cartridge-style game on real hardware.
Source: https://x.com/amrayupon/status/2112173859126608313
Tools they used: Codex, ModRetro Chromatic plugin
Category: Vibe coding & apps

Please:
1. Ask me 3 short questions about my situation (accounts I have, budget, what I want the output to look like).
2. Propose a step-by-step plan using these tools or cheaper alternatives, with the time and cost of each step. Use official pricing pages; say "check pricing" if unsure.
3. Then do the setup with me one step at a time, waiting for my OK before anything that sends messages, posts publicly, spends money or deletes data.
4. Finish with a checklist to run it again next time.

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Guides for this use case

How to port or remake a classic game with AI · How to use Claude Code skills and plugins · How to vibe code a game with AI · How to run multiple coding agents together

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