An in game way of editing how a particle works, and making it its own particle, like GOL.
Examples:
I think that this could add a lot of creative potential to saves. Not sure about the coding dificulty though, or the use in lag saves/tptmp crashers. If this is already a mod, please lmk. Thank you for reading! :D
Like CUST, but for non-life types; that could be useful, but it would be hard to make.