This is pretty nice, although one nitpick: each click on the Randomize Interactions button places the site in my history again, with the updated matrix settings. So, before someone realizes it, their recent browser history is full of Particle Life instances. I feel like that's not ideal, but I'm not sure the best way to fix it.

Oh yeah that’s not ideal, that should be a replace! Thanks for pointing this out.

Feature request: There are too many particles and they have little space to make weird stuff. Perhaps you can add a button to kill half of the particles and another to duplicate them.

Great work. It would be nice to see the interactions wrap to make a more seamless experience. The particles themselves do seem to wrap around the edges, but the forces do not.