Particle Life Planets & Rockets
Particle Life, which I believe was originally developed by John Conway.
Here I show planets, which have a core layer and an outer layer. The planets are made by making on or more very tightly attracted group. There is also a layer of green that is less attracted to the other colors, and repulsed from itself.
I also have "Rockets" where one color is strongly attracted to another color, but the second color is repelled from the first. If the attraction is stronger than the repulsion, what we get is particles chasing each other.
I saw this first on a Code Parade video
Unfortunately I'm not currently able to share the code for this. This is due to the fact that I work at Google as a software engineer, and thus need to get permission before releasing projects. (Note, this is a personal youtube channel though, and unaffiliated with my employer) If I end up going through the permission process in the future, I'll update this and share the code.