It's very cool!
Just like iphones get the latest/newest features after top of the line Androids.
Safari Tech Preview may have it enabled by default.
Unfortunately, the demo itself is not responsive to the screen size.
Why someone would want to simulate a slime mold is something I don't understand, but more power to ya. =)
The most interesting results I got were from having multiple "variants" and giving each variant parameters for their attraction to agents of their own/other type. Implementation-wise it was a variant tag for each agent and a matrix of attraction coefficients as a uniform. Playing with the params resulted in interesting behaviors, like one variant chasing another around while they both try to avoid a third.
If you're looking for an addition to this project, I'd recommend giving it a try!