I like minibb's ability to have a forum where non-registered "guests" can post. I tested that on your trial board where you had such a forum, which allowed a guest to just enter any name (which hadn't been taken) and post.
But, to prevent spammers, I would like to be able to have a "real person" test question (like, "What's the last name of a golfer named tiger?" or whatever question I would decide) which an anonymous poster would have to answer prior to being able to post. This is to prevent robot posting. I have used such a "real person" test on a guestbook that is open to posting by non-registered users and it worked well to stop bots from posting.
Is such a mod available? Or is this a feature already implemented?
I am aware that you have a catcha mod which is discussed here:https://www.minibb.com/captcha.html
And I will indeed purchase that captcha mod (that is very reasonable pricing) even if there is a "real person" test question mod available. But, I have used both approaches and I prefer the real person test question to captcha. Captcha codes get read by machines, but cleverly phrased real person questions prevent spammers much more successfully.