I recently worked with a client to hook in https://www.cleverbot.com/ so that the bot would reply to you if you @ mentioned it. You could have a conversation with it. Unfortunately that project was closed-sourced or I would share, but the concept is straightforward. It is also fairly light-weight as an extension because all the ‘AI’ is performed remotely and you are leveraging the bots existing capabilities.
On a related note you can embed Interactive Fiction in a Topic like so:
You could do the same, but use Posts for each step in your journey, but I think that would be hugely wasteful of forum resources and who’s going to read that again unless they are looking for a walkthrough? (now that’s an idea!)