This was posted on hackaday[0] last week with a link to a youtube video. In the video, the author of the project goes into depth about some of the challenges they encountered and changes they made in good technical detail.
I think the complaints in this thread are not in the spirit of HN. Let's do better.
Direct link to the video: https://www.youtube.com/watch?v=qzpZQe7JT-o
It's quite interesting, and describes how the developer used COBOL to implement a raycasting algorithm and generate a stream of PPM images to to pipe into FFplay. There's zero evidence of this being written in Claude; there are multiple clips of the developer working in VSCode, where the Claude plugin doesn't even appear to be installed.