I want to draw your attention to:
It is a new forum for us to share experimental Particle System features with you.
There are 2 features available already, and the most exciting one is a new “Standard Particle Shader”, which aims to provide all the core particle shader functionality in a simple interface.
@richardkettlewell I don’t see the standard particle shader any longer. Was it removed?
It’s no longer experimental / preview, so it comes with the base Unity installation from 2018.1 on. It is a little odd that the original threads have been deleted. 
Sorry… it was getting a little bit crowded in there and hard to see what features were still experimental, so I archived everything that we’ve shipped.