There was a recent thread about a tool that "proves" a human actually wrote something via an animated edit history (https://news.ycombinator.com/item?id=48699969). I commented that I can recognize AI writing regardless of such tools, and received some pushback...so, I wanted to be sure I wasn't lying to myself, and made a little game that shows samples or writing in a variety of styles, and you pick whether it's human or AI. It's harder than I expected, especially with current frontier models, but I think AI prose is still detectable.