The author shared this prompt in their post.
“Create a 1-on-1 card game like Hearthstone. Just make it. As best you can.
THIS IS INSANE 😱 I built an entire Hearthstone-style game with Opus 5.5 in one go. The gameplay and UX are almost identical — only the graphics are different. And this was literally my entire prompt: “Create a 1-on-1 card game like Hearthstone. Just make it. As best you can.