On Sunday I spent a couple of hours building a short 2d platformer ("Prince of Persia" style). What's interesting is how I built it. I went for a zero-code approach, and built the whole thing using OpenAI Codex CLI and agent skills (with the progressive disclosure paradigm).

You can play the game here: https://acatovic.github.io/gothicvania-codex-demo/

You can see the full code, agent skills and a complete writeup here: https://github.com/acatovic/gothicvania-codex-demo

Some takeaways:

* This was one of the most enjoyable experiences ever!

* Applying harness engineering with progressive disclosure is incredibly powerful - I treated my SKILL.md as simply a ToC (a "skills map") and took it from there

* Implement -> Evaluate loops are key - I used Playwright and an evaluation checklist and the agent built and corrected automagically

* I used PROGRESS.md as a memory/log mechanism for the agent, and a way to minimize context noise

* The game dev agent was steered by the DESIGN-DOCUMENT.md, stipulating game objectives, layout and mechanics

* I used progressive prompting - I built up the game piece wise - starting with basic player mechanics, then adding tiles, NPCs, interactions, sounds, menus - one prompt at a time

Zero code written by me. Never even looked at the game engine (Phaser) API - just gave the skills a link to the documentation. The future is here!

Credits to ansimuz (gothicvania assets) and Pascal Belisle (music).

*NOTE:* The assets were *NOT* created by AI. Backgrounds and probably tiles you could generate with AI, but sprites are not quite there yet (I tried a number of different models). Something to explore fully in the future.

Enjoy and let me know what you think!