xNode
Unity Node Editor: Lets you view and edit node graphs inside Unity
...Thinking of developing a node-based plugin? Then this is for you. You can download it as an archive and unpack to a new unity project, or connect it as a git submodule. xNode is super userfriendly, and intuitive and will help you reap the benefits of node graphs in no time. With a minimal footprint, it is ideal as a base for custom state machines, dialogue systems, decision-makers, etc. No runtime reflection (unless you need to edit/build node graphs at runtime. In this case, all reflection is cached.) Custom node-inspector code is very similar to regular custom inspector code. ...