The mysteries are all written by LLMs. Some are better than others, but most work nicely.
The web app is written in go with templ HTML templates, HTMX for on-page interactivity, SSE for content updates, and a turn-based game engine written as a Temporal workflow.
Check out the mystery gen write up for more info: https://blog.apartment304.com/whodunit-llm-murder-mysteries