Kangaroo 'boom'... with relationships

I’m wondering if Daniel Piker would be able to share the definition for his ‘Boom’ video: https://vimeo.com/212795528. I have an idea for a design generation tool that would utilize something like this but with relationships of attraction between the particles. See http://lauren.design/projects/garden-generator for more info about the project.

Here’s a demo similar to what is in that video:

What does the anchor component do here? I disconnected it and it seems to work the same.