Looking for Topic Tree Type of Plugin

Hello,

I’m building a site that encourages skill building and I want to connect posts together in what I can only call a topic tree. Think about games you may have played and your character has to master lower level skills to build up to higher ones or you have to research things to enable higher game functions and each research builds ones below.

I’ve ran every search I could thing of and didn’t come up with anything. I have to believe there is something that lets you build links between posts.

Thanks