I Gave Codex One Image to Build a Web Game Demo

Try Lian Wu (Mac): https://lianwu.app/yt In the Codex era, building a demo should start with image generation. Not because the image is final art. Because a strong image gives an agent a clearer target than a long, flat spec. It shows layout, mood, UI density, game feel, and the kind of details that are hard to describe in text. In this video, I start with a fantasy brick breaker concept image. Then I give that image to Codex and ask it to turn the direction into a playable frontend demo. The goal is not to ship a complete game. The goal is to show a faster way to start: image first, agent build, human review, then refine. Play the demo: https://fantasy-break.marvinswift.com What I cover: 1. Generating the concept image 2. Using the image as a visual brief 3. Letting Codex build the first version 4. Reviewing what worked and what felt off 5. Improving the UI and gameplay feel 6. Showing the live demo Next, I will make a separate video about the Cloudflare deployment and custom domain setup. Marvin Builds is where I build and test real AI-agent workflows in public.