"play" in this case does not imply that the product should be game or something like that but something that the user can interact with. From the Show HN rules: "On topic: things people can run on their computers or hold in their hands. For hardware, you can post a video or detailed article. For books, a sample chapter is ok"

You cannot play with a chapter of a book but it is acceptable. So, the "play" does not used with its exact meaning

I don't think that's an accurate interpretation of the rules.

There have been plenty of Chrome extensions that are Show HNs: https://hn.algolia.com/?q=Chrome.google.com+Show+Hn